Fix security: enable CSP and eliminate shell injection in entrypoint

- Enable restrictive Content Security Policy in tauri.conf.json instead
  of null (disabled), restricting scripts/connects to self + Tauri IPC
- Fix shell injection in entrypoint.sh by replacing su -c with direct
  git config --file writes, preventing names with quotes (e.g. O'Brien)
  from breaking startup or enabling code execution

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

container/entrypoint.sh

@@ -82,17 +82,18 @@ if [ -n "$GIT_TOKEN" ]; then
     echo "https://oauth2:${GIT_TOKEN}@github.com" >> "$CRED_FILE"
     echo "https://oauth2:${GIT_TOKEN}@gitlab.com" >> "$CRED_FILE"
     echo "https://oauth2:${GIT_TOKEN}@bitbucket.org" >> "$CRED_FILE"
-    su -s /bin/bash claude -c "git config --global credential.helper 'store --file=$CRED_FILE'"
+    git config --global --file /home/claude/.gitconfig credential.helper "store --file=$CRED_FILE"
     unset GIT_TOKEN
 fi
 
 # ── Git user config ──────────────────────────────────────────────────────────
 if [ -n "$GIT_USER_NAME" ]; then
-    su -s /bin/bash claude -c "git config --global user.name '$GIT_USER_NAME'"
+    git config --global --file /home/claude/.gitconfig user.name "$GIT_USER_NAME"
 fi
 if [ -n "$GIT_USER_EMAIL" ]; then
-    su -s /bin/bash claude -c "git config --global user.email '$GIT_USER_EMAIL'"
+    git config --global --file /home/claude/.gitconfig user.email "$GIT_USER_EMAIL"
 fi
+chown claude:claude /home/claude/.gitconfig 2>/dev/null || true
 
 # ── Claude instructions ──────────────────────────────────────────────────────
 if [ -n "$CLAUDE_INSTRUCTIONS" ]; then