feat: Implement junior fees dashboard and reconciliation

- Add dual-sheet architecture to pull attendance from both adult and junior spreadsheets.
- Introduce parsing rules to isolate juniors (e.g. above '# Treneri', tier 'J').
- Add new endpoints `/fees-juniors` and `/reconcile-juniors` to track junior attendances and match bank payments.
- Display granular attendance components showing adult vs. junior practices.
- Add fee rule configuration supporting custom pricing exceptions for specific months (e.g. Sep 2025) and merging billing periods.
- Add `make sync-2025` target to the Makefile for convenience.
- Document junior fees implementation logic and rules in prompts/outcomes.

Co-authored-by: Antigravity <antigravity@google.com>

Makefile

@@ -19,6 +19,7 @@ help:
 	@echo "  make image  - Build an OCI container image"
 	@echo "  make run    - Run the built Docker image locally"
 	@echo "  make sync        - Sync Fio transactions to Google Sheets"
+	@echo "  make sync-2025   - Sync Fio transactions for Q4 2025 (Oct-Dec)"
 	@echo "  make sync-2026   - Sync Fio transactions for the whole year of 2026"
 	@echo "  make infer       - Infer payment details (Person, Purpose, Amount) in the sheet"
 	@echo "  make reconcile   - Show balance report using Google Sheets data"
@@ -43,11 +44,14 @@ image:
 	docker build -t fuj-management:latest -f build/Dockerfile .
 
 run:
-	docker run -it --rm -p 5001:5001 fuj-management:latest
+	docker run -it --rm -p 5001:5001 -v $(CURDIR)/.secret:/app/.secret:ro fuj-management:latest
 
 sync: $(PYTHON)
 	$(PYTHON) scripts/sync_fio_to_sheets.py --credentials .secret/fuj-management-bot-credentials.json
 
+sync-2025: $(PYTHON)
+	$(PYTHON) scripts/sync_fio_to_sheets.py --credentials .secret/fuj-management-bot-credentials.json --from 2025-10-01 --to 2025-12-31 --sort-by-date
+
 sync-2026: $(PYTHON)
 	$(PYTHON) scripts/sync_fio_to_sheets.py --credentials .secret/fuj-management-bot-credentials.json --from 2026-01-01 --to 2026-12-31 --sort-by-date