feat(fusion_accounting_reports): line_resolver service for report row computation

Pure-Python helper that resolves a fusion.report's line_specs against
account_totals -> ordered list of report row dicts. Supports three spec
types: account_type_prefix (sum accounts by type), account_id (single
account, drill-downable), and compute='subtotal' (sum last N rows).

Comparison-period support: variance_pct computed automatically when
comparison_totals are supplied.

5 new tests, 32 total passing.

Made-with: Cursor

fusion_accounting_reports/__manifest__.py

@@ -1,6 +1,6 @@
 {
     'name': 'Fusion Accounting Reports',
-    'version': '19.0.1.0.1',
+    'version': '19.0.1.0.2',
     'category': 'Accounting/Accounting',
     'summary': 'AI-augmented financial reports (P&L, balance sheet, trial balance, GL).',
     'description': """