fix(acp): keep mode state synchronized

[xinyuan0801]

Related Issue

Resolve #2828

Problem

ACP initialized both mode projections to default regardless of the engine's active permission or plan state. The cached projection also became stale when permission or plan mode changed at runtime, so an IDE could display a mode that did not match the behavior actually enforced by the engine.

What changed

• Expose the current permission mode and its change event through the Klient agent facade.
• Derive ACP mode state from the engine's permission and plan state when a session is created or restored, with plan mode taking precedence.
• Keep both ACP projections synchronized at runtime by coalescing permission and plan invalidations into an authoritative refresh, discarding stale snapshots and suppressing intermediate states during session/set_mode.
• Push current_mode_update and config_option_update from the same reconciled snapshot and stop in-flight refreshes from publishing after session disposal.
• Cover configured and persisted modes, runtime permission changes, plan entry and exit, atomic plan-to-permission transitions, event routing, and both memory and IPC transports.
• Add a patch changeset for the corrected ACP behavior. No documentation update is needed because the existing mode configuration and protocol surface are unchanged.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

[changeset-bot]

🦋 Changeset detected

Latest commit: 427658b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@moonshot-ai/kimi-code	Patch

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