feat(agent): source-grounded project roadmap conversations

[Timverhoogt]

Summary

First read-only slice of roadmap delivery goal 2; builds on merged workspace PR #65.

• Add host-owned exact project/roadmap registration through Homebody bridge setting REACHY_AGENT_PROJECTS_JSON, disabled by default.
• Discover project IDs and read only each registered Markdown roadmap, with source lines/hash/ranges/freshness and truthful truncation.
• Keep short redacted project dialogue in the existing device/generation lease, serialize turns, reread source for narrow follow-ups, and clear via real idle-expiry timers and authorization transitions.
• Constrain project discussions to catalog/roadmap tools server-side; prevent the discovery exception from chaining home actions. No new shell, arbitrary-file, project execution or provider authority.
• Preserve descriptor-scoped no-follow file reads; nonblocking opens reject FIFOs before they can pin the worker.
• Document implementation boundaries and remaining native session/work-launcher gates.

Verified

• 927 non-browser tests passed; Ruff and git diff --check passed.
• 23 actual Chromium regression checks passed (explicit fixtures; no new UI assets).
• Built wheel and verified exact project/broker/bridge resources and robot policy inside it; companion CLI direct-script imports work.
• Actual Homebody roadmap read through the broker with source evidence and no side effects.
• Actual raw-photo-agent ROADMAP.md read through the broker from a temporary checkout at b764b5e3774639b8e62188358baecd9a42640fdb: all 50 lines, SHA-256 53aa7c3dd2f0b14e84b92e5cba15e1c50da7993116753a95d4fc1fd337858c42, no truncation, no execution authority.
• Authenticated aiohttp voice-route tests use explicitly deterministic provider fixtures, not real-model quality claims.

Scope / pending gates

This is not delivery goal 2 complete. No native Hermes/Desktop project session or coding launcher, no native run/tool stream, no durable jobs/ready-to-test notifications. No live service/catalog configuration, deployment, microphone/camera/motion test or real-provider spoken acceptance performed. The temporary RAW checkout is verification input, not production registration. Native project/session selection and separately authorized host-side execution remain next.