Implement Dashboard consolidation + Performance logging

Features:
- Add unified "Dashboard Complet" sheet (Excel) with all 9 sections
- Add unified "Dashboard Complet" page (PDF) with key metrics
- Fix VALOARE_ANTERIOARA NULL bug (use sumar_executiv_yoy directly)
- Add PerformanceLogger class for timing analysis
- Remove redundant consolidated sheets (keep only Dashboard Complet)

Bug fixes:
- Fix Excel formula error (=== interpreted as formula, changed to >>>)
- Fix args.output → args.output_dir in perf.summary()

Performance analysis:
- Add PERFORMANCE_ANALYSIS.md with detailed breakdown
- SQL queries take 94% of runtime (31 min), Excel/PDF only 1%
- Identified slow queries for optimization

Documentation:
- Update CLAUDE.md with new structure
- Add context handover for query optimization task

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude/commands/session-start.md

@@ -0,0 +1,13 @@
+Start a new development session by creating a session file in `.claude/sessions/` with the format `YYYY-MM-DD-HHMM-$ARGUMENTS.md` (or just `YYYY-MM-DD-HHMM.md` if no name provided).
+
+The session file should begin with:
+1. Session name and timestamp as the title
+2. Session overview section with start time
+3. Goals section (ask user for goals if not clear)
+4. Empty progress section ready for updates
+
+After creating the file, create or update `.claude/sessions/.current-session` to track the active session filename.
+
+Confirm the session has started and remind the user they can:
+- Update it with `/project:session-update`
+- End it with `/project:session-end`