feat(analyzer): add Claude CLI JSON format support and session management

- Extend parse_json_response() to support both flat and Claude CLI formats
  - Extract result, sessionId, and metadata fields
  - Support metadata.files_changed, metadata.has_errors, completion_status
  - Parse progress_indicators array for confidence boosting
- Add session management functions for continuity tracking:
  - store_session_id(): Persist session with ISO timestamp
  - get_last_session_id(): Retrieve stored session ID
  - should_resume_session(): Check session validity (24-hour expiration)
- Add get_epoch_seconds() to date_utils.sh for cross-platform epoch time
- Auto-persist sessionId to .session_id file during response analysis
- Add 16 new TDD tests for Claude CLI format and session management
- Update documentation for v0.9.6 (239 tests total)

Test count: 239 (up from 223)

lib/date_utils.sh

@@ -39,3 +39,15 @@ get_next_hour_time() {
 get_basic_timestamp() {
     date '+%Y-%m-%d %H:%M:%S'
 }
+
+# Get current Unix epoch time in seconds
+# Returns: Integer seconds since 1970-01-01 00:00:00 UTC
+get_epoch_seconds() {
+    date +%s
+}
+
+# Export functions for use in other scripts
+export -f get_iso_timestamp
+export -f get_next_hour_time
+export -f get_basic_timestamp
+export -f get_epoch_seconds