ci: run ruff from uv.lock instead of uvx latest

`uvx ruff` resolves to the newest ruff release on every run, so the
0.16.0 release turned CI red on main and on open PRs without any code
change: its expanded default rule set reports 700+ findings and its
formatter now rewrites code blocks in markdown. Using `uv run ruff`
pins the linter to the version in uv.lock (0.15.4), so lint results
only move when the lockfile is intentionally updated.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: 1egoman

.github/workflows/ruff.yml

@@ -18,8 +18,10 @@ jobs:
       - name: Install the project
         run: uv sync --all-extras --dev
 
+      # Use the ruff version pinned in uv.lock rather than uvx's latest release,
+      # so lint results only change when the lockfile is intentionally updated.
       - name: Ruff livekit-api
-        run: uvx ruff check --output-format=github .
+        run: uv run ruff check --output-format=github .
 
       - name: Check format
-        run: uvx ruff format --check .
+        run: uv run ruff format --check .