fix: restore tree dropped by 6d224861; land stem95su gdrive-sync (10m) [ci skip]

6d224861 came from a --no-checkout worktree whose empty index made the
commit drop every file except two. This restores 05b50d2b's full tree and
correctly adds stacks/stem95su/gdrive-sync.tf + the service-catalog stem95su
entry. Forward-only (parent=6d224861, no force-push); [ci skip] since the
live infra was never applied from the broken commit.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

stacks/excalidraw/project/Dockerfile

@@ -0,0 +1,22 @@
+FROM golang:1.21-alpine AS builder
+
+WORKDIR /app
+COPY go.mod ./
+COPY main.go ./
+COPY static/ ./static/
+
+RUN go build -o excalidraw-library .
+
+FROM alpine:latest
+
+RUN apk --no-cache add ca-certificates
+
+WORKDIR /app
+COPY --from=builder /app/excalidraw-library .
+
+ENV DATA_DIR=/data
+ENV PORT=8080
+
+EXPOSE 8080
+
+CMD ["./excalidraw-library"]