feat: expose embedded session host

[acedatacloud-dev]

Dependency node

1/6 for the internal debug-agent release. This is the runtime contract required by PlatformService.

Summary

• expose coding_bridge.embed.SessionHost so a server can host Coding Bridge sessions behind its own WebSocket/JWT transport
• reuse the existing session registry, action dispatcher, permissions, history, Claude provider, resume guard, and file checkpointing
• add provider allowlisting and a caller-owned cwd policy for server-hosted use
• dual-license AceDataCloud-operated products while preserving AGPL-3.0-or-later for public users

Validation

• pytest tests/test_embed.py tests/test_connection.py tests/test_session.py tests/test_resume_guard.py -q — 49 passed
• changed-file ruff check — passed
• python -m build — wheel and sdist built
• git diff --check — passed

A local full-suite run also exercised 600+ tests but hit pre-existing environment-sensitive Codex capability/log-capture/portal-thread failures; the same Codex assertion fails on the unmodified primary checkout. GitHub Linux/Python matrix remains authoritative.

Rollout / rollback

• no existing daemon behavior changes; the embedding API is additive and inherits the tested dispatcher
• rollback by reverting this PR; no data migration
• after merge, publish the next CalVer and pin that version in PlatformService

Out of scope

• no debug-agent service in this repository
• no relay/pairing changes

Review

Adversarial review was not requested.

🤖 Generated with Claude Code