feat(legal): resolve DEC-020 — dual-license under Apache-2.0 OR MIT

Closes the only previously-open decision in the register. Chanora is
now dual-licensed under either:

  * Apache License, Version 2.0 (LICENSE-APACHE), OR
  * MIT License (LICENSE-MIT)

at the recipient's option. This is the standard Rust-ecosystem
permissive model and is compatible with every direct dependency
in the PoC tree:

  tsclientlib          MIT OR Apache-2.0
  flutter_rust_bridge  MIT
  cpal                 Apache-2.0
  rusqlite             MIT
  keyring              MIT OR Apache-2.0
  hound                Apache-2.0
  ndk-context, jni, android_logger, regex, serde, tokio,
  tracing, thiserror, zeroize, etc.   MIT OR Apache-2.0

and with the Flutter framework's BSD-3-Clause.

Files added:
  - LICENSE-APACHE  Apache 2.0 license text.
  - LICENSE-MIT     MIT license text with the standard 2026 copyright
                    line.

Files updated:
  - LICENSE     Now the dual-license aggregator. Includes the standard
                Apache-2.0 inbound-contribution clause ("Unless you
                explicitly state otherwise, any contribution
                intentionally submitted for inclusion in Chanora by you,
                as defined in the Apache-2.0 license, shall be
                dual-licensed as above, without any additional terms or
                conditions.").
  - NOTICE      Rewritten with the dual-license declaration and an
                inventory of direct dependencies with their upstream
                licenses. Transitive deps remain to be enumerated by
                build tooling (cargo about, Flutter LicenseRegistry).
  - README.md   §License section rewritten to point at LICENSE-APACHE
                and LICENSE-MIT.
  - docs/governance/product-decision-register.md v0.9.5 → v0.9.6:
    DEC-020 status: Open → Accepted. §4 license row updated. §6
    collapsed: every previously-Proposed or Open decision in the
    register is now resolved. DEC-012 legal review remains as a
    release-gating *work* item, but is not an open decision.
  - docs/governance/poc-results-summary.md v0.3.0 → v0.4.0:
    RISK-PoC-003 closed. DEC-020 row moved out of 'Still open'.

This is a license-model commitment, not a substitute for the
DEC-012 legal review. Per DEC-012 the actual legal review work
(transitive-dep OSS obligations, trademark registrability, final
sign-off on the non-affiliation wording) must still be completed
before any public/store release; that is sign-off work, not an
architectural decision.

Decision register state after this commit:
  Accepted:       23 of 23 unique decisions
  Open/Deferred:  0
  Proposed:       0

CHANGELOG.md

@@ -8,6 +8,8 @@ This project is expected to follow a Conventional Commits style workflow.
 
 ### Added
 
+- `LICENSE-APACHE` — Apache License Version 2.0 text (DEC-020).
+- `LICENSE-MIT` — MIT License text (DEC-020).
 - Initial repository foundation files.
 - Documentation-first project structure.
 - `justfile` with `format`, `lint`, `test`, `verify-docs`, and
@@ -48,6 +50,23 @@ This project is expected to follow a Conventional Commits style workflow.
 
 ### Changed
 
+- **DEC-020 license resolved.** Chanora is now dual-licensed under
+  **Apache-2.0 OR MIT** (recipient's choice), the standard
+  Rust-ecosystem permissive model. Compatible with every direct
+  dependency (`tsclientlib`, `flutter_rust_bridge`, `cpal`, `rusqlite`,
+  `keyring`, etc.) and with the Flutter framework's BSD-3-Clause.
+  `LICENSE` rewritten as a dual-license aggregator pointing at
+  `LICENSE-APACHE` and `LICENSE-MIT`. `NOTICE` rewritten with current
+  direct-dependency attributions. `README.md` §License updated.
+- `docs/governance/product-decision-register.md` bumped to v0.9.6:
+  DEC-020 status promoted from Open to Accepted. §4 license row
+  updated. §6 collapsed: there is no longer any open decision —
+  DEC-012 legal review remains as a *work* item, not a pending
+  decision. Change-history entry added.
+- `docs/governance/poc-results-summary.md` bumped to v0.4.0:
+  RISK-PoC-003 closed. DEC-020 row moved from the "Still open"
+  section into the closed table.
+
 - `docs/governance/product-decision-register.md` bumped to v0.9.5:
   owner confirmation on all 17 previously-Proposed decisions
   (DEC-001..010, 012, 015..019, 021). Sixteen were Accepted as