ci: Add Codecov flags for component and Python version coverage tracking

Add codecov.yml with flag definitions for unit, integration, and CLI
components with path-based filtering. Update workflow to tag uploads
with Python version flags (py3.12, py3.13).

Author: github-actions

.github/workflows/tests.yml

@@ -67,6 +67,7 @@ jobs:
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           files: coverage.xml
+          flags: unittests,py${{ matrix.python-version }}
           fail_ci_if_error: true
           verbose: true
 

codecov.yml

@@ -0,0 +1,33 @@
+coverage:
+  status:
+    project:
+      default:
+        target: auto
+    patch:
+      default:
+        target: auto
+
+flag_management:
+  default_rules:
+    carryforward: true
+
+  individual_flags:
+    - name: unit
+      paths:
+        - src/ryandata_address_utils/parsers/
+        - src/ryandata_address_utils/models/
+        - src/ryandata_address_utils/core/
+        - src/ryandata_address_utils/validation/
+        - src/ryandata_address_utils/data/
+      carryforward: true
+
+    - name: integration
+      paths:
+        - src/ryandata_address_utils/pandas_ext.py
+        - src/ryandata_address_utils/service.py
+      carryforward: true
+
+    - name: cli
+      paths:
+        - src/ryandata_address_utils/setup_cli.py
+      carryforward: true