fix(voice): synchronize local model install state

[wgqqqqq]

Summary

• bind composer model capability state to the currently selected local model and ignore stale async status responses
• report post-download processing as verifying instead of leaving the UI at downloading 100%
• write and validate the install record inside staging before publishing the final model directory
• add regressions for model-selection races and staged install publication

Root cause

The model payload was moved into its final directory before the install record and required-file hashes were finished. speech_list_models could therefore report the model as installed and enable Use while the active download task still emitted downloading at 100%. The composer also retained an unkeyed capability snapshot, so a response for the previous model could overwrite the selected model state.

Verification

• cargo test -p bitfun-services-integrations --no-default-features --features speech --lib speech:: (6 passed)
• pnpm --dir src/web-ui run test:run src/flow_chat/components/voice/useComposerVoiceInput.test.tsx (7 passed)
• pnpm run check:web
• git diff --check

Remote scenarios

Exercised on the local Desktop/service path. Remote Workspace, Remote Control, Peer Device Mode, and Detached Dispatch were not runtime-tested; the service-side state transition remains platform-neutral and does not change the transport contract.

AI-assisted change; fully tested with the focused checks above.

[wgqqqqq]

Fixed the macOS CI failure in bb6e7a539. The test created lowercase and uppercase spellings of the same UUID path; on the default case-insensitive APFS volume those names alias the same directory, so deleting the valid stale staging directory also made the uppercase assertion disappear. The uppercase non-canonical fixture now uses a distinct UUID, preserving the cleanup-policy assertion across case-sensitive and case-insensitive filesystems.

Verified on macOS with:
cargo test -p bitfun-desktop packaged_frontend_cache_removes_only_stale_transaction_directories --lib