Fix setup wizard and installer for fresh-install flow

- setup_manager: fall back to update_password if admin already exists
  (installer bootstrap creates admin; wizard now updates rather than fails)
- install.sh: chown repo to SUDO_USER instead of pic user so the
  invoking operator can run make update without git safe.directory errors
- test: update mock to also stub update_password when testing total auth failure

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

install.sh

@@ -245,10 +245,11 @@ else
     log_ok "Repository cloned to ${PIC_DIR}"
 fi
 
-# Ensure the pic user owns the directory
-chown -R "${PIC_USER}:${PIC_USER}" "$PIC_DIR"
-# Allow any user to run git commands in this directory (installer runs as root,
-# operators run as themselves — git safe.directory prevents ownership errors)
+# Give the invoking user (or pic if run directly as root) ownership of the repo
+# so they can run `make update` and other git commands without sudo.
+REPO_OWNER="${SUDO_USER:-${PIC_USER}}"
+chown -R "${REPO_OWNER}:${REPO_OWNER}" "$PIC_DIR"
+# Allow all users to run git commands here regardless of who owns the files
 git config --system --add safe.directory "$PIC_DIR" 2>/dev/null || true
 
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