fix: clear all 7 tracked tech-debt items

[artyomsv]

Resolves every entry tracked under techdebt/ — one high-priority goroutine-leak, four medium correctness/perf items, and two low-priority hardening items. Code-review findings on top of the initial cleanup are folded in.

Fixed

• daemon: Stop() now closes d.shutdown via shutdownOnce + wraps teardown in stopOnce, so idleChecker / memReport ctx-bridge / sendGhostChunked exit on every Stop path. server.Stop() runs before the final snapshot so no IPC ACK can outlive the on-disk state. (techdebt 2-2)
• daemon: snapshot() takes one consistent SnapshotState and reuses it for both workspace.json and ghost-buffer flush via the new workspaceStateFromSnapshot helper, eliminating the off-by-one pane-count drift between the two halves. Periodic ticker still calls snapshot() directly so the safety-net write cannot be starved by sustained event traffic resetting the debounce timer. (techdebt 3-2)
• daemon: paneSourceAdapter collapsed from 7 methods (6 PluginMu acquisitions per pane per tick) to a single Snapshot() that acquires PluginMu once with defer-Unlock for panic safety. (techdebt 3-2)

Changed

• mcp: get_memory_report halves IPC latency by embedding the tab list directly in MemoryReportRespPayload; the bridge falls back to bare tab IDs against pre-1.10 daemons. (techdebt 3-2)
• tui: notes-mode header gains a persistent reverse-video focus badge (INPUT / PANE) with three-tier degrade for narrow widths. Defence-in-depth against synthesised mouse-click input redirection. (techdebt 4-2)

Tests

• New daemon unit tests: TestIsValidHexID, TestWorkspaceStateFromSnapshot, TestStop_ClosesShutdownChannel, TestStop_Idempotent.
• New cmd/quil unit tests: TestBuildTabMemSummaries (4 cases incl. pre-1.10 daemon nil-Tabs path).
• New TUI tests: dialog handlers (settings/confirm), notes header badge focus + narrow-width truncation.
• New Windows-tagged PTY tests covering SetCWD/SetEnv/newWithSize/ pre-start safety/WaitExit sentinel. (techdebt 4-2)
• New //go:build integration suite for daemon Start/Stop and IPC-driven MemoryReport round-trip + snapshot consistency.