feat(lifecycle): stuck detection + heartbeat lifecycle + SDK tool blocklist

Replaces the two overlapping old mechanisms (30-min setTimeout kill in
container-runner, 10-min heartbeat STALE_THRESHOLD reset in host-sweep)
with message-scoped stuck detection anchored to the processing_ack claim
age + an absolute 30-min ceiling that extends for long-declared Bash
tools.

Old model problems:
- IDLE_TIMEOUT setTimeout fired on plain wall-clock time; slow-but-alive
  agents got killed at 30min regardless of activity
- 10-min STALE_THRESHOLD in the sweep was unreliable — the heartbeat is
  only touched on SDK events, so legitimate silent tool work (sleep 30,
  long WebFetch, npm install) looked identical to a hung container
- Two overlapping sources of truth for "when to let go of a container"

New model:
- Host sweep is the single source of truth.
- Container exposes a new `container_state` single-row table in outbound.db
  (schema added; container writes, host reads). PreToolUse hook writes
  current_tool + tool_declared_timeout_ms (read from Bash's tool_input);
  PostToolUse / PostToolUseFailure clear it.
- Sweep decides with a pure helper `decideStuckAction`:
    * absolute ceiling — kill if heartbeat age > max(30min, bash_timeout)
    * per-claim stuck  — kill if any processing_ack row has claim_age >
      max(60s, bash_timeout) AND heartbeat hasn't been touched since claim
    * otherwise ok
  Kill paths reset leftover processing rows with exponential backoff,
  reusing the existing retry machinery.

Tool blocklist expanded:
- AskUserQuestion (SDK placeholder; we have mcp__nanoclaw__ask_user_question)
- EnterPlanMode, ExitPlanMode, EnterWorktree, ExitWorktree (Claude Code UI
  affordances; would hang in headless containers)
PreToolUse hook is also defense-in-depth: if a disallowed tool name slips
through, it returns `{ decision: 'block' }` so the agent sees a clear
error instead of appearing stuck.

Removed:
- container-runner.ts: IDLE_TIMEOUT setTimeout, resetIdle callback on
  activeContainers entry, resetContainerIdleTimer export.
- delivery.ts: the resetContainerIdleTimer call on successful delivery.
- poll-loop.ts: IDLE_END_MS + its setInterval. Keeping the query open is
  cheaper than close+reopen (no cold prompt cache). Liveness is now a
  host-side concern.
- host-sweep.ts: 10-min STALE_THRESHOLD_MS + getStuckProcessingIds in the
  stale-detection path (still exported for kill reset).

Tests:
- src/host-sweep.test.ts — 9 tests for decideStuckAction covering: fresh
  heartbeat, absolute ceiling, absent heartbeat, Bash-timeout extension
  (both ceiling and per-claim), claim age below tolerance, heartbeat
  touched after claim, unparseable timestamps.

Ref: docs/v1-vs-v2/ACTION-ITEMS.md items 9, 6a, 10.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/db/session-db.ts

@@ -161,6 +161,47 @@ export function getStuckProcessingIds(outDb: Database.Database): string[] {
   ).map((r) => r.message_id);
 }
 
+export interface ProcessingClaim {
+  message_id: string;
+  status_changed: string;
+}
+
+/** Return processing_ack rows still in 'processing' with their claim timestamps. */
+export function getProcessingClaims(outDb: Database.Database): ProcessingClaim[] {
+  return outDb
+    .prepare(
+      "SELECT message_id, status_changed FROM processing_ack WHERE status = 'processing'",
+    )
+    .all() as ProcessingClaim[];
+}
+
+export interface ContainerState {
+  current_tool: string | null;
+  tool_declared_timeout_ms: number | null;
+  tool_started_at: string | null;
+}
+
+/**
+ * Read the container's current tool-in-flight state, if any. Returns null
+ * when either the table doesn't exist yet (older session DB) or no tool is
+ * active. Host sweep reads this to widen stuck-detection tolerance while
+ * Bash is running with a long declared timeout.
+ */
+export function getContainerState(outDb: Database.Database): ContainerState | null {
+  try {
+    const row = outDb
+      .prepare(
+        `SELECT current_tool, tool_declared_timeout_ms, tool_started_at
+           FROM container_state WHERE id = 1`,
+      )
+      .get() as ContainerState | undefined;
+    return row ?? null;
+  } catch {
+    // Table not present on older session DBs — treat as "no tool in flight".
+    return null;
+  }
+}
+
 // ---------------------------------------------------------------------------
 // messages_out (read-only from host)
 // ---------------------------------------------------------------------------