feat(agents): consolidate local client connections and prepare 0.5.0

[PeterGuy326]

Prepare RoleWeave 0.5.0 for the requested local Windows upgrade, consolidating the native Agent connection work from #594 with the desktop refinements already merged in #591.

The local Qwen Office connection owns dedicated employee sessions, bounded task progress/results, cancellation and pending-action reporting through separate desktop/WSL channels. Tools, approvals, model, account and usage remain client-owned and are described accurately in the UI. Codex readiness checks use the actual selected CLI and required launch capabilities. Employee settings retain the compact layout and no-op grant detection while Qwen employees expose name editing and client settings guidance. The external-adapter path retains its own model preflight contract.

Synchronize root/desktop package versions and lockfile metadata, freeze v0.5.0 notes, and move the applicable changelog entries into the versioned section. Public download links continue to point at published 0.4.0; this request creates a local Windows candidate and does not publish a tag or updater feed.

Validation:

• TypeScript build and renderer type checks passed.
• Interface integration: 80 regression tests passed.
• Provider/model/preflight tests: 44 passed, 1 platform skip.
• Engine persistence/HTTP contract: all 25 tests passed on WSL; the targeted native Windows engine-contract test passed.
• Local Windows candidate installer integrity passed: version 0.5.0, 114492989 bytes, SHA-256 883a947f38c99fff779f6756eb2b29f97c9b9fb0b18c98e62504e5aa7b9baa2f. The final installer will be rebuilt from the merged main commit.
• Local staging manifest passed. The clean-copy startup harness encountered a host Sogou helper that outlived the app and blocked temporary-directory cleanup; installed startup will be verified separately. The harness is unchanged.
• All GitHub CI checks passed on final head f70cf12, including Linux/macOS full checks, CodeQL, dependency review, Scorecard, native Windows/macOS staging, installers and layout parity. The final local installer is rebuilt from the exact squash-merged main commit before installation.

Refs #592