feat: add StorageAdapter abstraction and InMemoryAdapter with full test suite

- Introduce StorageAdapter protocol and InMemoryAdapter (thread-safe, in-memory)
  in engine/adapter.py to decouple storage from sync logic
- Refactor SyncEngine to accept a StorageAdapter, replacing the previous
  stub that returned an empty list
- Wire server to use SyncEngine + InMemoryAdapter, removing hardcoded
  SYNC_OPERATIONS fixtures
- Add tests for engine, adapter, generator, and types (tests/)
- Add pre-commit config (.pre-commit-config.yaml) with linting/formatting hooks
- Update pyproject.toml and uv.lock with new dev dependencies
- Clean up type annotations and CLI help strings across generator, server, and utils

.pre-commit-config.yaml

@@ -0,0 +1,55 @@
+# Pre-commit hooks for sync-protocol.
+#
+# Install:  uv run --group dev pre-commit install
+# Run once: uv run --group dev pre-commit run --all-files
+
+default_language_version:
+  python: python3.12
+
+repos:
+  # ---------------------------------------------------------------------------
+  # General hygiene
+  # ---------------------------------------------------------------------------
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v5.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-toml
+      - id: check-json
+      - id: check-merge-conflict
+      - id: debug-statements
+
+  # ---------------------------------------------------------------------------
+  # Black — code formatter
+  # ---------------------------------------------------------------------------
+  - repo: https://github.com/psf/black
+    rev: 26.5.1
+    hooks:
+      - id: black
+        language_version: python3.12
+
+  # ---------------------------------------------------------------------------
+  # Ruff — linter + import sorter (auto-fix on commit)
+  # ---------------------------------------------------------------------------
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.16.4
+    hooks:
+      - id: ruff
+        args: [--fix, --exit-non-zero-on-fix]
+
+  # ---------------------------------------------------------------------------
+  # Mypy — static type checker
+  # ---------------------------------------------------------------------------
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v2.3.1
+    hooks:
+      - id: mypy
+        args: [--config-file, pyproject.toml]
+        additional_dependencies:
+          - "pydantic>=2.13.4"
+          - "pydantic-settings>=2.15.0"
+          - "click>=8.4.2"
+          - "jinja2>=3.1.6"
+          - "pytest>=9.1.1"