docs: add generic adapter sample

[Hisakazu333]

Summary

Add a runnable generic-adapter.mjs sample that exports a staged bundle, builds local bridge request payloads, emits a receipt, and rolls back the export root. Align the adapter docs with the live lifecycle words already used by the desktop bridge.

Scope

• Feature or behavior change
• Bug fix
• Security hardening
• UI-only change
• Documentation
• Packaging or release

Verification

• cargo fmt --all -- --check
• cargo test --workspace
• npm run build
• npm audit --omit=dev
• npm run security:audit
• git diff --check
• node --test docs/examples/generic-adapter/generic-adapter.test.mjs
• node docs/examples/generic-adapter/generic-adapter.mjs export|plan|receipt|rollback

Release Impact

• No installer rebuild needed
• Rebuild macOS DMG
• Rebuild Windows installer
• Update SHA256
• Update release notes

Notes

• The sample only uses the existing session-summary bundle fixture.
• bundle.detail preview status is saved; the imported receipt uses imported.
• actions.results and events.poll share the same lifecycle words: queued, running, succeeded, failed, conflict, cancelled.