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/tools/hashline-edit/constants.ts

@@ -8,3 +8,4 @@ export const HASHLINE_DICT = Array.from({ length: 256 }, (_, i) => {
 
 export const HASHLINE_REF_PATTERN = /^([0-9]+)#([ZPMQVRWSNKTXJBYH]{2})$/
 export const HASHLINE_OUTPUT_PATTERN = /^([0-9]+)#([ZPMQVRWSNKTXJBYH]{2}):(.*)$/
+export const HASHLINE_LEGACY_REF_PATTERN = /^([0-9]+):([0-9a-fA-F]{2,})$/