fix: resolve 5 deployment blockers (runtime-fallback race, hashline legacy, tmux spawn, db open)

- runtime-fallback: guard session.error with sessionRetryInFlight to prevent
  double-advance during active retry; expand session.stop abort to include
  sessionAwaitingFallbackResult; remove premature pendingFallbackModel clearing
  from auto-retry finally block
- hashline-edit: add HASHLINE_LEGACY_REF_PATTERN for backward-compatible
  LINE:HEX dual-parse in parseLineRef and normalizeLineRef
- tmux-subagent: defer session on null queryWindowState; unconditionally
  re-queue deferred session on spawn failure (not just close+spawn)
- ultrawork-db: wrap new Database(dbPath) in try/catch to handle corrupted DB
- event: add try/catch guards around model-fallback logic in message.updated,
  session.status, and session.error handlers

src/hooks/runtime-fallback/auto-retry.ts

@@ -143,10 +143,6 @@ export function createAutoRetryHelpers(deps: HookDeps) {
     } catch (retryError) {
       log(`[${HOOK_NAME}] Auto-retry failed (${source})`, { sessionID, error: String(retryError) })
     } finally {
-      const state = sessionStates.get(sessionID)
-      if (state?.pendingFallbackModel === newModel) {
-        state.pendingFallbackModel = undefined
-      }
       sessionRetryInFlight.delete(sessionID)
     }
   }