fix: reconcile pending Monarch transactions

[eshaffer321]

What changed

• Reconcile cached categorized orders when Monarch replaces a pending transaction with its posted transaction.
• Reapply cached category, notes, and splits without rerunning AI categorization.
• Mark writes against pending transactions as provisional and finalize them after posting.
• Avoid unsafe Amazon/Walmart multi-charge consolidation while any matched transaction is pending.
• Add regression coverage and document the incident.

Root cause

Monarch can replace a pending transaction with a new posted transaction ID. The sync recorded the old pending ID as successfully categorized, so later runs treated the order as complete and never reapplied the category/splits to the replacement transaction.

Validation

• go test ./...
• go vet ./...
• golangci-lint run --timeout=5m
• Live Amazon dry-run confirmed the affected air-filter order resolves to the posted replacement and would reapply cached state without a Monarch write.

[codecov]

Codecov Report

❌ Patch coverage is 58.88889% with 111 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.70%. Comparing base (687e971) to head (44fb6c4).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/application/sync/reconciliation.go	54.27%	68 Missing and 23 partials ⚠️
internal/application/sync/types.go	54.54%	10 Missing ⚠️
internal/application/sync/orchestrator.go	72.22%	4 Missing and 1 partial ⚠️
internal/application/sync/handlers/walmart.go	75.00%	2 Missing and 2 partials ⚠️
internal/infrastructure/storage/mock.go	80.00%	0 Missing and 1 partial ⚠️

❌ Your patch status has failed because the patch coverage (58.88%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #83      +/-   ##
==========================================
- Coverage   64.70%   64.70%   -0.01%     
==========================================
  Files          49       50       +1     
  Lines        6715     6969     +254     
==========================================
+ Hits         4345     4509     +164     
- Misses       2050     2118      +68     
- Partials      320      342      +22     

Flag	Coverage Δ
unittests	64.70% <58.88%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
internal/application/sync/handlers/amazon.go	66.26% <100.00%> (+0.97%)	⬆️
internal/application/sync/recording.go	40.58% <100.00%> (+10.82%)	⬆️
internal/infrastructure/storage/sqlite.go	76.16% <100.00%> (ø)
internal/infrastructure/storage/mock.go	52.75% <80.00%> (+0.50%)	⬆️
internal/application/sync/handlers/walmart.go	61.23% <75.00%> (+0.45%)	⬆️
internal/application/sync/orchestrator.go	39.39% <72.22%> (+6.06%)	⬆️
internal/application/sync/types.go	30.40% <54.54%> (-1.47%)	⬇️
internal/application/sync/reconciliation.go	54.27% <54.27%> (ø)

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