Add session status file creation rule across workflow commands

Updates all workflow commands to create .workflow/session_status.jsonl if it doesn't exist when checking for active sessions. This ensures consistent behavior across:

- gemini-chat.md: Added creation rule and updated workflow pseudocode
- gemini-execute.md: Added session file creation requirement
- gemini-mode.md: Updated session check process
- workflow/action-plan.md: Updated both session check locations
- task/replan.md: Added creation rule to session validation
- task/breakdown.md: Updated session check process
- workflow/brainstorm.md: Added creation rule to session registry query

Also includes cleanup of deprecated command files (context.md, sync.md) and documentation updates for task creation complexity escalation.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.claude/commands/workflow/session.md

@@ -179,24 +179,6 @@ When starting a new session, the following files are automatically generated:
 *Use /workflow:plan to populate this document*
 ```
 
-### Backup and Recovery System
-
-#### Automatic Backup Creation
-- **Trigger Events**: Session pause, critical state changes, error recovery
-- **Backup Location**: `.workflow/WFS-[topic-slug]/.backups/`
-- **Retention**: Last 5 backups per session
-- **Format**: Timestamped JSON and markdown backups
-
-#### Backup Structure
-```
-.workflow/WFS-[topic-slug]/.backups/
-├── session-2025-09-07-14-00.json    # Session state backup
-├── session-2025-09-07-15-30.json
-├── session-2025-09-07-16-45.json
-├── IMPL_PLAN-2025-09-07-14-00.md    # Document backups  
-└── TODO_LIST-2025-09-07-15-30.md
-```
-
 #### Recovery Operations
 - **Auto-recovery**: On session corruption or inconsistency
 - **Manual recovery**: Via `/workflow:session recover --from-backup`