feat(repository): add composite primary key support (#640)

Adds support for composite (multi-column) primary keys in the repository layer.

Changes:
- Add PrimaryKeyType type alias supporting scalar, tuple, and dict formats
- Add helper methods for composite key handling:
  - _is_composite_pk(): Check if model has composite PK
  - _build_pk_filter(): Build WHERE clause for PK lookup
  - _extract_pk_value(): Extract PK value(s) from instance
  - _pk_values_present(): Check if all PK values are set
  - _normalize_pk_values_to_tuples(): Convert PK values to tuples for bulk ops
- Update get() to support composite keys (tuple or dict input)
- Update delete() to support composite keys
- Update delete_many() to use tuple_().in_() for efficient bulk operations
- Cache PK columns in __init__ for performance

The implementation follows SQLAlchemy's native patterns and maintains
full backward compatibility for single-column primary keys.

Closes #189

Author: cofin

.gitignore

@@ -186,6 +186,6 @@ requirements
 AGENTS.md
 CLAUDE.md
 GEMINI.md
-
+.agent/
 tools/scripts/detect_mcp_tools.py
 .geminiignore

.pre-commit-config.yaml

@@ -2,7 +2,7 @@ default_language_version:
   python: "3"
 repos:
   - repo: https://github.com/compilerla/conventional-pre-commit
-    rev: v4.3.0
+    rev: v4.4.0
     hooks:
       - id: conventional-pre-commit
         stages: [commit-msg]
@@ -22,7 +22,7 @@ repos:
       - id: unasyncd
         additional_dependencies: ["ruff"]
   - repo: https://github.com/charliermarsh/ruff-pre-commit
-    rev: "v0.15.0"
+    rev: "v0.15.2"
     hooks:
       # Run the linter.
       - id: ruff