docs(spec): baseline 0.9.5 — v1 audio + PTT lifecycle redesign

Add SysRS-303/304, SysDes-149/150/151, SRS-204/205/206/207,
SAD-081/082/083, SDD-094/095/096/097, DEC-029/030.

Captures the v1 lifecycle redesign:
- Drop manual Start-audio button; audio engine is bound to voice-channel
  join/leave (ensure_running on first join, shutdown_if_idle on last
  leave). Output stream opens regardless of mic-permission state so
  listen-only is a first-class flow.
- TransmitMode enum (Ptt / Continuous / VoiceActivity-reserved).
  Default Ptt on fresh install. Persisted per identity.
- PTT release tail: 200 ms default (0-500 ms configurable) before
  transmit gate closes, avoiding clipped trailing syllables.
- Hard-mute toggle overrides transmit gate regardless of mode/PTT.
- Bridge surface: drop start_audio/stop_audio; add
  voice_join(channel_id) / voice_leave() and BridgeEvent::VoiceState.

DEC-029 rejects Flutter global-hotkey packages (hotkey_manager,
super_hot_key) for PTT: they wrap RegisterHotKey/RegisterEventHotKey
which consume the key and don't fire key-up, wrong primitive for PTT.
Native Rust DesktopPttBackend (SDD-083/084/085) stays authoritative.

DEC-030 defers Voice Activity Detection to P1. RMS / WebRTC VAD /
Silero VAD trade-off review (binary-size, dependency-surface, CPU
profile) postponed; TransmitMode::VoiceActivity reserved on the enum
surface so a P1 increment is non-breaking.

Validator clean: 304/151/207/83/97 IDs, strict layered sourcing
preserved, no new warnings beyond the pre-existing 35 old-package-name
filenames.

docs/governance/document-index.md

@@ -1,7 +1,7 @@
 # Document Index
 
 **Document type:** Configuration / Documentation Control  
-**Version:** 0.9.2  
+**Version:** 0.9.5  
 **Status:** Baseline Candidate  
 **Language:** English  
 **Product:** Chanora  
@@ -86,3 +86,4 @@ SysDes -> SYS.4
 |---|---|---|
 | 0.9.2 | 2026-05-14 | Converted documentation package to repository-oriented docs folder structure and updated internal filename references. |
 | 0.9.3 | 2026-05-15 | Added `docs/architecture/desktop-ptt-architecture.md` to the controlled document set. |
+| 0.9.5 | 2026-05-15 | Bumped controlled-set version to 0.9.5 for the v1 audio + PTT lifecycle refactor: SysRS-303..304, SysDes-149..151, SRS-204..207, SAD-081..083, SDD-094..097, and two new governance decisions DEC-029 (Flutter global-hotkey packages rejected for PTT) and DEC-030 (Voice Activity Detection deferred to P1). No controlled files added or removed; existing files updated in place under strict layered sourcing. |