refactor(python-dev): swap pip -> uv pip for project install

uv is now pre-baked into the base image
(agent-runtimes/images/base/Dockerfile) and is faster than pip with
better retry on transient network failures. Closes the last runtime
hang vector for project-deps install — apt install was removed 2026-09-06
in 0c57972f-pre-bake work but the pip install -e line in init.sh
remained. uv pip install is the equivalent operation with the new
pre-baked tooling.

Refs F-WE-PDIV/RCA-2026-09-04-zombies.

harnesses/capabilities/python-dev/v1/init.sh

@@ -18,10 +18,14 @@ if [[ -f "/workspace/pyproject.toml" ]]; then
     # Activate virtual environment
     source .venv/bin/activate
 
-    # Install project in development mode with all dependencies
-    pip install -e ".[dev,test]" 2>/dev/null || pip install -e . 2>/dev/null || {
+    # Install project in development mode with all dependencies.
+    # Switched from `pip` to `uv pip` 2026-09-09 — uv is now pre-baked into
+    # the base image (agent-runtimes/images/base/Dockerfile) and is faster,
+    # has better retry on transient network failures, and the only remaining
+    # runtime-install hang vector for project deps.
+    uv pip install -e ".[dev,test]" 2>/dev/null || uv pip install -e . 2>/dev/null || {
         echo "Could not install with extras, trying basic install..."
-        pip install -e .
+        uv pip install -e .
     }
 
     echo "Project installed in development mode"