feat(session)!: persist watch and connect rules

[BegoniaHe]

Summary

Persist /session watch and /session connect as directed SQLite edges with stable rule_ids, wall-clock watch TTL (floor 1 second), and IM /session links / /session unlink for creators and same-config operators.

Related issue

Fixes #193
Related: #192

Behavior

• Unexpired watches and all connects survive process restart; expired watches are deleted and notify the listener.
• Watch duration is 1–864000 seconds on the wall clock; connect stays unbounded and rejects extra tokens.
• Same-direction watch recreate keeps rule_id and resets TTL; connect retarget is 1:1; watch↔connect replace each other.
• /session links and /session unlink <rule_id> are IM-only. Creators see and can revoke their own rules after role loss; current-config instance_operator sees/revokes rules touching that config; operator/root see and revoke all.
• SessionWatch now has rule_id; expires_at is wall-clock UTC unix seconds; list() still returns only the actor's watches.

Non-goals

• pair / unpair (#194)
• /session filter (#195)
• Dashboard / OpenAPI CRUD
• Connect TTL
• Extending SessionBridgeCapability with links/unlink

Implementation notes

SessionBridgeManager remains the public owner. Live grants, connect 1:1, and store IO live in private SessionBridgeState. The new session_bridge_rules table includes S2/S3 columns (pair_id, match, except, header) written with S1 defaults. Restore rebuilds Subject.from_id and re-authorizes; lost permission deletes the row. Adapter-unavailable deliveries skip without deleting the rule.

This is a plugin SDK semantic break for SessionWatch and MIN_WATCH_TTL_SECONDS.

Validation

uv run ruff check <touched python>
uv run pytest tests/unit/db/test_session_bridge_store.py tests/unit/db/test_schema.py tests/unit/db/test_protocols.py tests/unit/test_session_bridge.py tests/unit/test_session_commands.py tests/unit/test_message_protocol.py tests/unit/test_core_lifecycle.py tests/unit/test_builtin_command_extensions.py::test_non_public_builtin_commands_declare_the_planned_actions
make check-md

Not run: make check, make test-blocking.

Compatibility and risk

Breaking for plugins that assume monotonic SessionWatch.expires_at or MIN_WATCH_TTL_SECONDS == 60. Restore AuthContext is reconstructed from subject.kind without a new column; deny deletes the row (fail closed). No OpenAPI change.

Checklist

• A Feature request Issue exists for large work, or this is a small, obvious addition.
• The change is focused and does not include unrelated refactoring.
• I added or updated tests, or explained why tests are not practical.
• User-visible behavior updates both docs/zh/ and docs/en/.
• OpenAPI, generated client, docs/public/openapi.json, and tests change together when routes or schemas change.
• No secrets committed. Runtime Python deps update pyproject.toml, requirements.txt, and uv.lock together.
• I did not restore legacy shims, Python <3.14 fallbacks, or upstream publish/docs URLs as fork artifacts.
• Breaking API or behavior changes use ! and a BREAKING CHANGE: footer.
• I will not merge this PR myself. Merge needs a human maintainer review plus a separate AI-assisted review (AI_POLICY.md).
• AI use follows AI_POLICY.md. Keep exactly one author note below. Do not fabricate the other.

Agent note

Goal: ship #193 S1 of the session-bridge persistence stack. Paths: new session_bridge_rules store, SessionBridgeState, manager restore/lifecycle, IM links/unlink, bilingual command/authorization/send-message docs. Checks actually run are listed under Validation; make check and blocking pytest were not run. Residual risk: reconstructed restore context for rare subject kinds, and the SDK wall-clock/rule_id break. Tools: OpenCode / grok-4.6.