feat: production release with React SPA, file attachments, and deploy tooling

Backend:
- Add file_handlers.go: presigned upload/download for item attachments
- Add item_files.go: item file and thumbnail DB operations
- Add migration 011: item_files table and thumbnail_key column
- Update items/projects/relationships DB with extended field support
- Update routes: React SPA serving from web/dist, file upload endpoints
- Update auth handlers and middleware for cookie + bearer token auth
- Remove Go HTML templates (replaced by React SPA)
- Update storage client for presigned URL generation

Frontend:
- Add TagInput component for tag/keyword entry
- Add SVG assets for Silo branding and UI icons
- Update API client and types for file uploads, auth, extended fields
- Update AuthContext for session-based auth flow
- Update LoginPage, ProjectsPage, SchemasPage, SettingsPage
- Fix tsconfig.node.json

Deployment:
- Update config.prod.yaml: single-binary SPA layout at /opt/silo
- Update silod.service: ReadOnlyPaths for /opt/silo
- Add scripts/deploy.sh: build, package, ship, migrate, start
- Update docker-compose.yaml and Dockerfile
- Add frontend-spec.md design document

build/package/Dockerfile

@@ -0,0 +1,25 @@
+FROM node:22-alpine AS frontend
+WORKDIR /app
+COPY web/package.json web/package-lock.json ./
+RUN npm ci
+COPY web/ ./
+RUN npm run build
+
+FROM golang:1.24-alpine AS builder
+RUN apk add --no-cache git
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+COPY --from=frontend /app/dist ./web/dist
+RUN CGO_ENABLED=0 go build -o /silod ./cmd/silod
+RUN CGO_ENABLED=0 go build -o /silo  ./cmd/silo
+
+FROM alpine:3.20
+RUN apk add --no-cache ca-certificates wget
+COPY --from=builder /silod /usr/local/bin/silod
+COPY --from=builder /silo  /usr/local/bin/silo
+COPY --from=frontend /app/dist /var/www/silo
+EXPOSE 8080
+ENTRYPOINT ["silod"]
+CMD ["-config", "/etc/silo/config.yaml"]