feat(fusion_accounting_ai): 5 new financial reports AI tools

Adds financial_reports.py tools module with 5 fusion-engine-routed
tools registered in TOOL_DISPATCH:

- fusion_run_report
- fusion_get_anomalies
- fusion_generate_commentary
- fusion_drill_down_report_line
- fusion_compare_periods

Each tool guards on 'fusion.report.engine' being in the registry and
otherwise returns a structured error so the chat agent can surface a
clear "module not installed" message.

6 new TransactionCase tests (including a TOOL_DISPATCH registration
sanity check).

Made-with: Cursor

fusion_accounting_ai/services/tools/__init__.py

@@ -9,11 +9,12 @@ from .inventory import TOOLS as INVENTORY_TOOLS
 from .adp import TOOLS as ADP_TOOLS
 from .reporting import TOOLS as REPORTING_TOOLS
 from .audit import TOOLS as AUDIT_TOOLS
+from .financial_reports import TOOLS as FINANCIAL_REPORTS_TOOLS
 
 TOOL_DISPATCH = {}
 for tools_dict in [
     BANK_RECON_TOOLS, HST_TOOLS, AR_TOOLS, AP_TOOLS, JOURNAL_TOOLS,
     MONTH_END_TOOLS, PAYROLL_TOOLS, INVENTORY_TOOLS, ADP_TOOLS,
-    REPORTING_TOOLS, AUDIT_TOOLS,
+    REPORTING_TOOLS, AUDIT_TOOLS, FINANCIAL_REPORTS_TOOLS,
 ]:
     TOOL_DISPATCH.update(tools_dict)