merge: integrate origin/dev into modular-enforcement branch

Resolves all merge conflicts, preserving our split module structure
while integrating all dev changes:
- Custom agent summaries support (parseRegisteredAgentSummaries)
- Background notification queue (enqueueNotificationForParent)
- Atlas shared git-worktree module (collectGitDiffStats, formatFileChanges)
- Ralph-loop withTimeout + DEFAULT_API_TIMEOUT=5000
- Session recovery assistant_prefill_unsupported error type
- Atlas agentOverrides forwarding
- Config handler plan model demotion (buildPlanDemoteConfig)
- Delegate-task agentOverrides, promptSyncWithModelSuggestionRetry, variant
- LSP init timeout + stale init detection
- isPlanFamily function + task-continuation-enforcer hook
- Handoff command

src/plugin/tool-execute-before.ts

@@ -88,6 +88,7 @@ export function createToolExecuteBeforeHandler(args: {
       if (command === "stop-continuation" && sessionID) {
         hooks.stopContinuationGuard?.stop(sessionID)
         hooks.todoContinuationEnforcer?.cancelAllCountdowns()
+        hooks.taskContinuationEnforcer?.cancelAllCountdowns()
         hooks.ralphLoop?.cancelLoop(sessionID)
         clearBoulderState(ctx.directory)
         log("[stop-continuation] All continuation mechanisms stopped", {