feat(SessionStore): auto-create session records if missing

- Added functionality to automatically create a session record in the database if it does not exist when storing observations or session summaries.
- Updated `storeObservation` and `storeSummary` methods to include checks for existing session records and insert new records as needed.
- Added logging for auto-created session records for better traceability.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "claude-mem",
-  "version": "4.1.1",
+  "version": "4.2.0",
   "description": "Memory compression system for Claude Code - persist context across sessions",
   "keywords": [
     "claude",