fix(docker): switch alpine to node:22-slim for pre-built better-sqlite3

Alpine uses musl libc; better-sqlite3 has no pre-built musl binaries so
it always compiles from source (installs 300 MB of gcc/g++/python3,
takes 3-5 min). node:22-slim (Debian) has glibc so prebuild-install
downloads a pre-built binary instead — build stays under 1 minute.

Changes:
- Both stages: node:22-alpine -> node:22-slim
- deps stage: remove apk/build-tool installation (not needed)
- runtime stage: remove apk libstdc++ install (present in debian-slim)
- HEALTHCHECK: wget -> node built-in http (wget absent from debian-slim)
- docker-compose.yaml: same healthcheck fix

Dockerfile

@@ -1,21 +1,24 @@
 # ---------------------------------------------------------------------------
 # Stage 1 — deps: install production dependencies only
 # ---------------------------------------------------------------------------
-FROM node:22-alpine AS deps
+# node:22-slim (Debian slim) is used instead of Alpine so that
+# better-sqlite3 can use its pre-built glibc binaries rather than
+# compiling from source (Alpine uses musl libc — no pre-builds exist).
+# This keeps build times fast (~1 min vs ~5 min for source compilation).
+FROM node:22-slim AS deps
 
 WORKDIR /app
 
 # Copy manifests and install production deps only (no devDependencies).
-# build-base provides the C++ toolchain needed to compile better-sqlite3's
-# native addon. It stays in the deps stage and is NOT copied to runtime.
+# prebuild-install will download the pre-built better-sqlite3 binary for
+# linux-x64-glibc, so no C++ toolchain is needed here.
 COPY package.json package-lock.json ./
-RUN apk add --no-cache python3 make g++ && \
-    npm ci --omit=dev
+RUN npm ci --omit=dev
 
 # ---------------------------------------------------------------------------
 # Stage 2 — runtime image (minimal attack surface)
 # ---------------------------------------------------------------------------
-FROM node:22-alpine AS runtime
+FROM node:22-slim AS runtime
 
 LABEL org.opencontainers.image.title="sofarr"
 LABEL org.opencontainers.image.description="Personal media download dashboard for *arr services"
@@ -30,11 +33,7 @@ LABEL custom.hardware.requirement="None - runs on any Docker-supported platform
 # The /app directory is owned by root; data directory is owned by node
 WORKDIR /app
 
-# libstdc++ is required at runtime to load the better-sqlite3 native addon.
-# The build tools (g++, make, python3) remain in the deps stage only.
-RUN apk add --no-cache libstdc++
-
-# Copy production deps from deps stage
+# Copy production deps from deps stage (includes pre-built better-sqlite3)
 COPY --from=deps /app/node_modules ./node_modules
 
 # Copy application source owned by root (read-only at runtime)
@@ -53,8 +52,9 @@ USER node
 
 EXPOSE 3001
 
-# HEALTHCHECK — Docker will restart the container if this fails 3 times
+# HEALTHCHECK — Docker will restart the container if this fails 3 times.
+# Uses node's built-in http module (no wget/curl needed in slim image).
 HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
-  CMD wget -qO- http://localhost:3001/health || exit 1
+  CMD node -e "require('http').get('http://localhost:3001/health',r=>{process.exit(r.statusCode===200?0:1)}).on('error',()=>process.exit(1))"
 
 CMD ["node", "server/index.js"]