fix: replace python3 with py/jq throughout scripts and docs

Windows Store python3 stub returns exit 49 instead of running Python.
Replace with: py (Windows launcher) for actual Python code, jq for
simple JSON extraction. Reorder fallback loops to try py first.
Add Bash(py:*) to settings.local.json allowlist.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/scripts/sync.sh

@@ -39,7 +39,7 @@ echo -e "${GREEN}[OK]${NC} Working directory: $(pwd)"
 
 # Detect Python interpreter — verify it actually runs (Windows Store stub passes command -v but fails to execute)
 PYTHON=""
-for candidate in python3 python; do
+for candidate in py python3 python; do
     if command -v "$candidate" >/dev/null 2>&1; then
         if "$candidate" -c "import sys; sys.exit(0)" >/dev/null 2>&1; then
             PYTHON="$candidate"
@@ -48,7 +48,7 @@ for candidate in python3 python; do
     fi
 done
 if [ -z "$PYTHON" ]; then
-    echo -e "${RED}[ERROR]${NC} No Python interpreter found (need python or python3)"
+    echo -e "${RED}[ERROR]${NC} No Python interpreter found (tried: py, python3, python)"
     exit 1
 fi