fix(ios,macos): preserve Silero @_cdecl exports across Xcode Archive

The Apple CoreML Silero VAD backend resolves six @_cdecl Swift symbols
via dlsym(RTLD_DEFAULT) at runtime in the Rust audio crate. Local
flutter build paths preserved those symbols, but Xcode Archive (the
path used for TestFlight and App Store uploads) silently stripped them
through two independent mechanisms, causing Rust to fall back to
WebRTC VAD on every shipped build.

Both stripping mechanisms are now neutralised:

* ld dead-strip: OTHER_LDFLAGS now whitelists each of the six
  chanora_silero_vad_* symbols via repeated `-Xlinker -exported_symbol`
  pairs in ios/Flutter/{Release,Debug}.xcconfig and
  macos/Flutter/Flutter-{Release,Debug}.xcconfig.
* install-time strip: STRIP_STYLE is set to `non-global` in the same
  four xcconfigs so the post-link strip phase no longer drops exported
  global text symbols from the Archive product. Cost: ~264 bytes per
  binary; verified `xcrun strip` vs `xcrun strip -x` behaviour.

Self-test wired into both AppDelegates: at launch on a utility queue,
ChanoraSileroSelfTest resolves all six symbols through dlsym (the same
path the Rust runtime uses, not a direct call that would mask the bug
class) and exercises create → reset → process → destroy. Result is
logged via NSLog and surfaces in Console.app / idevicesyslog.

A post-link verify_silero_exports.sh build phase runs nm -gU on the
final Archive binary and fails the build if any of the six symbols are
missing. Empirically caught the original Archive regression that
flutter build --no-codesign did not.

CocoaPods bridge podspecs now emit a proper .dSYM via dsymutil so
TestFlight crash reports are symbolicated; Cargo.toml release profile
sets `debug = true` because dsymutil needs DWARF in the input dylib.

macOS chanora_bridge.podspec PATH inserts /opt/homebrew/opt/rustup/bin
ahead of /opt/homebrew/bin so rustup's cargo (which has the
x86_64-apple-darwin target installed) wins over the homebrew rust
formula that is aarch64-only.

iOS Podfile target renamed from `Runner` to `Chanora` to match the
Xcode target name shipped in the project (the workspace and scheme
already referenced Chanora; the Podfile mismatch produced lint
warnings during `pod install`).

ITSAppUsesNonExemptEncryption=false declared in both Info.plist files
so TestFlight and App Store Connect uploads skip the export-compliance
prompt; Chanora uses only platform-provided TLS.

.gitignore now covers Xcode archive bundles, IPA exports, dSYM
directories, the local macOS release zip, and agent/tooling state
directories so generated TestFlight artifacts no longer appear in
git status.

End-to-end verified by headless archive:
  xcodebuild -workspace Runner.xcworkspace -scheme Runner \
    -configuration Release -destination 'generic/platform=iOS' \
    -archivePath /tmp/chanora.xcarchive archive CODE_SIGNING_ALLOWED=NO
nm -gU on the resulting .app/Chanora binary shows all six
chanora_silero_vad_* symbols present.

apps/chanora_flutter/macos/Runner/AppDelegate.swift

@@ -7,6 +7,10 @@ class AppDelegate: FlutterAppDelegate {
   override func applicationDidFinishLaunching(_ notification: Notification) {
     super.applicationDidFinishLaunching(notification)
 
+    DispatchQueue.global(qos: .utility).async {
+      ChanoraSileroSelfTest.run()
+    }
+
     // Ask for microphone access on launch rather than on first
     // voice-channel join. Matches user expectations for a voice
     // chat client and saves the user from a surprising prompt

apps/chanora_flutter/macos/Runner/Info.plist

@@ -22,6 +22,8 @@
 	<string>$(FLUTTER_BUILD_NAME)</string>
 	<key>CFBundleVersion</key>
 	<string>$(FLUTTER_BUILD_NUMBER)</string>
+	<key>ITSAppUsesNonExemptEncryption</key>
+	<false/>
 	<key>LSMinimumSystemVersion</key>
 	<string>$(MACOSX_DEPLOYMENT_TARGET)</string>
 	<key>NSHumanReadableCopyright</key>

apps/chanora_flutter/macos/Runner/SileroCoreMLBridge.swift

@@ -1,4 +1,5 @@
 import CoreML
+import Darwin
 import Foundation
 import SileroCoreML
 
@@ -96,3 +97,97 @@ public func chanoraSileroVadFreeString(_ string: UnsafeMutablePointer<CChar>?) {
     guard let string else { return }
     free(string)
 }
+
+@objc public final class ChanoraSileroSelfTest: NSObject {
+    // Validates the same code path the Rust framework uses: dlsym(RTLD_DEFAULT) for all
+    // six @_cdecl symbols, then exercises create -> reset -> process -> destroy. Catches
+    // the dead-strip / linker-export class of bug that broke TestFlight; calling the Swift
+    // functions directly would mask it because direct calls bypass the dynamic symbol table.
+    @objc public static func run() {
+        let started = DispatchTime.now()
+
+        typealias CreateFn = @convention(c) () -> UnsafeMutableRawPointer?
+        typealias DestroyFn = @convention(c) (UnsafeMutableRawPointer?) -> Void
+        typealias ResetFn = @convention(c) (UnsafeMutableRawPointer?) -> Int32
+        typealias ProcessFn = @convention(c) (
+            UnsafeMutableRawPointer?, UnsafePointer<Float>?, Int, UnsafeMutablePointer<Float>?
+        ) -> Int32
+        typealias LastErrorFn = @convention(c) () -> UnsafeMutablePointer<CChar>?
+        typealias FreeStringFn = @convention(c) (UnsafeMutablePointer<CChar>?) -> Void
+
+        func resolve<T>(_ name: String, as type: T.Type) -> T? {
+            guard let raw = dlsym(UnsafeMutableRawPointer(bitPattern: -2), name) else {
+                return nil
+            }
+            return unsafeBitCast(raw, to: type)
+        }
+
+        let names = [
+            "chanora_silero_vad_create",
+            "chanora_silero_vad_destroy",
+            "chanora_silero_vad_reset",
+            "chanora_silero_vad_process",
+            "chanora_silero_vad_last_error",
+            "chanora_silero_vad_free_string",
+        ]
+        let missing = names.filter { dlsym(UnsafeMutableRawPointer(bitPattern: -2), $0) == nil }
+        if !missing.isEmpty {
+            NSLog("chanora_flutter: SileroCoreML self-test FAILED dlsym missing=\(missing.joined(separator: ","))")
+            return
+        }
+
+        guard
+            let create = resolve("chanora_silero_vad_create", as: CreateFn.self),
+            let destroy = resolve("chanora_silero_vad_destroy", as: DestroyFn.self),
+            let reset = resolve("chanora_silero_vad_reset", as: ResetFn.self),
+            let process = resolve("chanora_silero_vad_process", as: ProcessFn.self),
+            let lastError = resolve("chanora_silero_vad_last_error", as: LastErrorFn.self),
+            let freeString = resolve("chanora_silero_vad_free_string", as: FreeStringFn.self)
+        else {
+            NSLog("chanora_flutter: SileroCoreML self-test FAILED unsafeBitCast resolution")
+            return
+        }
+
+        func readError() -> String {
+            guard let ptr = lastError() else { return "unknown" }
+            let msg = String(cString: ptr)
+            freeString(ptr)
+            return msg
+        }
+
+        guard let handle = create() else {
+            let elapsedMs = elapsedMs(since: started)
+            NSLog("chanora_flutter: SileroCoreML self-test FAILED at create err=\(readError()) elapsed_ms=\(elapsedMs)")
+            return
+        }
+
+        let resetRc = reset(handle)
+        if resetRc != 0 {
+            destroy(handle)
+            let elapsedMs = elapsedMs(since: started)
+            NSLog("chanora_flutter: SileroCoreML self-test FAILED at reset rc=\(resetRc) err=\(readError()) elapsed_ms=\(elapsedMs)")
+            return
+        }
+
+        let chunkSize = SileroVADRunner.chunkSize
+        var probability: Float = 0
+        let samples = [Float](repeating: 0, count: chunkSize)
+        let processRc = samples.withUnsafeBufferPointer { buf -> Int32 in
+            process(handle, buf.baseAddress, chunkSize, &probability)
+        }
+
+        destroy(handle)
+
+        let elapsedMs = elapsedMs(since: started)
+        if processRc == 0 {
+            NSLog("chanora_flutter: SileroCoreML self-test OK probability=\(probability) elapsed_ms=\(elapsedMs)")
+        } else {
+            NSLog("chanora_flutter: SileroCoreML self-test FAILED at process rc=\(processRc) err=\(readError()) elapsed_ms=\(elapsedMs)")
+        }
+    }
+
+    private static func elapsedMs(since start: DispatchTime) -> String {
+        let ns = DispatchTime.now().uptimeNanoseconds &- start.uptimeNanoseconds
+        return String(format: "%.1f", Double(ns) / 1_000_000.0)
+    }
+}