chore: add comprehensive log patterns to gitignore, purge logs from history

- Add *.log.* and logs/ patterns to .gitignore
- Remove duplicate backend/logs and logs/app.log.1 entries
- Purge all log files, backend/logs/, and .axiom/runtime/ from
  entire git history via git-filter-repo

.gitignore

@@ -41,6 +41,9 @@ package-lock.json
 
 # Logs
 *.log
+*.log.*
+logs/
+backend/logs/
 backend/backend.log
 
 # OS
@@ -65,7 +68,6 @@ backend/mappings.db
 
 
 backend/tasks.db
-backend/logs
 backend/auth.db
 semantics/reports
 backend/tasks.db
@@ -77,11 +79,9 @@ node_modules/
 .venv/
 coverage/
 *.tmp
-logs/app.log.1
 audit_report.txt
 check_semantics.py
 docs_audit_report.txt
 run_mcp.py
 semantic_audit_report.md
 .axiom/checkpoints
-.axiom/runtime/belief_events.jsonl