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/shared/index.ts

@@ -46,5 +46,6 @@ export * from "./tmux"
 export * from "./model-suggestion-retry"
 export * from "./opencode-server-auth"
 export * from "./port-utils"
+export * from "./git-worktree"
 export * from "./safe-create-hook"
 export * from "./truncate-description"