fix(release): count .md changes in package matrix; use --frozen for pytest

Review findings from the PR:
- release.py's has_changes() only counted .py/.ts files, so the README
  touches meant to enroll the four TS packages in the npm matrix would
  have been ignored. Include .md — READMEs ship inside the published
  package (npm tarball / PyPI long_description), so doc changes are
  release-relevant.
- uv run --frozen pytest for consistency with the job's other uv calls.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AViME1R9ES2UXT1uQDx1TG

.github/workflows/release.yml

@@ -142,7 +142,7 @@ jobs:
         working-directory: src/${{ matrix.package }}
         run: |
           if [ -d "tests" ] || [ -d "test" ]; then
-            uv run pytest
+            uv run --frozen pytest
           else
             echo "No tests directory, skipping"
           fi

scripts/release.py

@@ -113,7 +113,9 @@ def has_changes(path: Path, git_hash: GitHash) -> bool:
         )
 
         changed_files = [Path(f) for f in output.stdout.splitlines()]
-        relevant_files = [f for f in changed_files if f.suffix in [".py", ".ts"]]
+        # .md counts as a change: READMEs ship inside the published package
+        # (npm tarball / PyPI long_description)
+        relevant_files = [f for f in changed_files if f.suffix in [".py", ".ts", ".md"]]
         return len(relevant_files) >= 1
     except subprocess.CalledProcessError:
         return False