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>

Gemfile.lock

@@ -0,0 +1,24 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    bigdecimal (4.0.1)
+    csv (3.3.5)
+    dotenv (3.2.0)
+    httparty (0.24.2)
+      csv
+      mini_mime (>= 1.0.0)
+      multi_xml (>= 0.5.2)
+    mini_mime (1.1.5)
+    multi_xml (0.8.1)
+      bigdecimal (>= 3.1, < 5)
+
+PLATFORMS
+  ruby
+  x86_64-linux
+
+DEPENDENCIES
+  dotenv
+  httparty
+
+BUNDLED WITH
+   2.6.7