Initial implementation of the reconciliation script

Standalone Ruby script reconciling GoCardless payments, Dolibarr
invoices (via API), and Shine bank statements. Three-pass engine:
GC↔Dolibarr matching, open invoice audit, payout↔bank verification.
Includes dry-run and --fix mode to auto-mark Dolibarr invoices as paid.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,13 @@
+# Credentials — never commit
+.env
+
+# Input data — contains customer PII and financial data
+gocardless/
+shine/
+
+# Output
+tmp/
+
+# Ruby
+.bundle/
+vendor/bundle/