chore: bump Dockerfile base to node:24-alpine and add git for npm git-URL deps

Deploy CI was failing on `npm ci` because the base image lacked `git`,
which npm needs to resolve `bchen-sqlite-migrate` from its git URL.
Bumping the base from node:22-alpine to node:24-alpine in the same change
aligns the image with authd's stack (npm 11.x) — both native deps support
Node 24 prebuilds.

Dockerfile

@@ -1,7 +1,7 @@
-FROM node:22-alpine
+FROM node:24-alpine
 
-# Install native build tools for bcrypt
-RUN apk add --no-cache python3 make g++
+# Install native build tools for bcrypt/better-sqlite3 + git for npm git-URL deps
+RUN apk add --no-cache python3 make g++ git
 
 WORKDIR /app