chore: remove all internal references and rename Walkie Talkie to Chorus

- Remove outbox/, REVIEW-R1R2R3-FULL.md, docs/, tests/cross_machine/
- Rename did:walkie → did:chorus throughout
- Rename all Walkie Talkie strings to Chorus
- Remove OpenClaw reference from README
- Zero traces of internal team names or project codenames

Author: LyonMask

.clippy.toml

@@ -1,4 +1,4 @@
-# walkie-talkie-core Clippy configuration
+# chorus-core Clippy configuration
 # https://doc.rust-lang.org/nightly/clippy/lint_configuration.html
 
 # ── Lint groups ──

README.md

@@ -103,7 +103,7 @@ cargo run --example cross_machine_test
 
 Chorus works across agent frameworks:
 
-- **OpenClaw** — Native integration via CLI
+- **Any framework** — Use the CLI or build on the core library
 - **Hermes (Nous Research)** — Verified cross-framework E2EE calls
 - **Any framework** — Use the CLI or build on the core library