feat: resume Muse ACP sessions without replay

[obviyus]

Problem

The adapter supports history-replaying session/load but not lightweight session/resume. Clients cannot rebind a retained Muse session with current MCP servers without replaying its full transcript.

Fix

• Advertise and implement stable ACP session/resume.
• Preserve live mode and configuration while replacing the current MCP server snapshot.
• Recreate adapter state from Muse's retained session store after close or process restart without replaying history.
• Keep the canonical original workspace and reject real workspace changes with a clear next step.
• Accept symlink-equivalent paths while storing the canonical target to prevent later symlink retargeting.
• Reject missing/deleted workspaces, extra workspace roots, unknown sessions, and mid-turn resume with typed ACP errors.

Verification

• Same-connection mode/config preservation and MCP refresh.
• Symlink-equivalent workspace acceptance and canonical storage.
• Changed, missing, and deleted workspace error paths.
• Additional-directory rejection.
• Mid-turn rejection with unchanged state.
• Real Muse echo: close → resume → no history replay → next prompt succeeds.
• npm run check
• npm run build
• npm run test:run — 125 passed, 2 live-provider tests skipped
• P1 autoreview — clean.
• Fable protocol, safety, and implementation reviews — clean.

Dependencies

This draft is stacked on #2, #3, and #4. Merge those first; GitHub will then reduce this PR to the resume implementation.