test: add 106 unit + smoke tests, 93% coverage

- pytest + respx + pytest-cov added as dev dependencies
- tests/smoke/test_registration.py: verify all 66 tools registered and unique
- tests/unit/: 12 files covering every tool — HTTP method, URL, params/body, errors
- tests/config.test.json + conftest.py: zero-network test setup via GITEA_CONFIG
- CLAUDE.md: developer guide with testing philosophy, pyramid, and commands
- server/gitea_mcp.py: get_commit, list_pr_files tools added
- README.md: tool count corrected to 66

server/gitea_mcp.py

@@ -484,6 +484,19 @@ def get_pr_diff(owner: str, repo: str, index: int, instance: str = "") -> Any:
         raise RuntimeError(f"Gitea API {r.status_code}: {r.text}")
     return {"diff": r.text}
 
+@mcp.tool()
+def list_pr_files(
+    owner: str, repo: str, index: int,
+    limit: int = 50, page: int = 1,
+    whitespace: str = "",
+    instance: str = "",
+) -> Any:
+    """List files changed in a pull request. whitespace: ignore-all|ignore-change|ignore-eol|show-all."""
+    return GET(instance, f"/repos/{owner}/{repo}/pulls/{index}/files", _strip({
+        "limit": limit, "page": page,
+        "whitespace": whitespace or None,
+    }))
+
 @mcp.tool()
 def list_pr_reviews(owner: str, repo: str, index: int, instance: str = "") -> Any:
     """List reviews on a pull request."""
@@ -617,6 +630,17 @@ def list_commits(
         "limit": limit, "page": page,
     }))
 
+@mcp.tool()
+def get_commit(
+    owner: str, repo: str, sha: str,
+    stat: bool = True, files: bool = True, verification: bool = False,
+    instance: str = "",
+) -> Any:
+    """Get a single commit by SHA or ref. stat=True includes diff stats, files=True includes changed files list."""
+    return GET(instance, f"/repos/{owner}/{repo}/git/commits/{_b(sha)}", _strip({
+        "stat": stat, "files": files, "verification": verification or None,
+    }))
+
 @mcp.tool()
 def compare_branches(owner: str, repo: str, base: str, head: str, instance: str = "") -> Any:
     """Compare two branches, tags, or commits."""