feat(mcp): resolve room-scoped servers at native OMP connection startup

[bandzalkin]

Rebased onto main d7ab3429cbdb (2026-10-15)

Rebased onto current main (after #709, #804, #789/#775, #796 and #802) as its prerequisite's commit plus one commit; head 4c393d0625a0d2d50b205b9d76d2452b3b8b36f6. Applied cleanly on rebased #763.

CHANGELOG.md edits are dropped: Release Please generates it.

Verified at the new head (macOS, Python 3.13): uv sync --all-packages --locked --extra dev, all pre-commit hooks, and the full pytest -q: 8686 passed, 739 skipped. Verification notes further down refer to the previous head.

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Summary

Resolve room-scoped external MCP servers at native OMP connection startup, under the same owner that creates and retires the connection. Related: #709.

Changes

• Resolve one snapshot for each fresh owned connection rather than caching room-dependent ambient servers across connections.
• Preserve Band's endpoint and secret-safe launch precedence, native RPC readiness, session restoration and cancellation behavior.
• Retain resolver/startup/cleanup ownership so interrupted startup cannot publish stale state or release resources still owned by a child.
• Update native OMP configuration documentation and user-facing Unreleased entries. Native migration and protected permission/tool envelopes belong to fix(integrations): preserve native OMP lifecycle and prompt authority #763, not this feature-only delta.

Stack and merge order

Prerequisite: #763 at 242a3c96268ee7f322213656a658ac5bb1c75133.
Exact feature-only range: 242a3c96268ee7f322213656a658ac5bb1c75133..4c393d0625a0d2d50b205b9d76d2452b3b8b36f6.
Merge #763, then #798. This main-targeted branch includes its prerequisite until that merge; the range above is resolver-only. Copilot and Codex/Claude lanes are independent.
All eight feature patches rebased unchanged. The inherited portability corrections calibrate natural decoder depth and prove positive peer/root/descendant settlement instead of requiring exit zero. The Windows launcher-hosted forced-close limit is disclosed in #763 and docs/acp.md; this PR does not make close graceful.

Testing

Prepared head differs from approved/tested ab77e212 only in CHANGELOG.md. At that tested head, permission/RPC/OMP-adapter scope: 142 passed on managed Python 3.13. The prerequisite correction scope passed managed 3.11/3.12/3.13 and fresh non-privileged Linux, with an explicit positively proved no-natural-window skip on 3.11. All five static hooks passed freshly at the prepared head.
Historical pre-correction all-adapter/OMP/registry scope at dd7181bf: 2827 passed, 3 skipped, 56 warnings; not a new-head full-suite claim. Source/index-delta stable patch ID remains 50b5b6044975fc3940661f78580c05438135e3d3, excluding only changelog/fork metadata. No new numeric fork graph is claimed.
send_event remains best-effort, not durable delivery. Local evidence is not native-provider/live-room acceptance or a remote matrix receipt; every new-head CI lane is awaited separately.

[bandzalkin]

Rebased onto current main (d7ab3429) at 4c393d0625a0; the description's new first section lists the conflict resolutions and the verification at this head.