feat: Go backend, enhanced search, new widgets, Docker deploy

Major changes:
- Add Go backend (backend/) with microservices architecture
- Enhanced master-agents-svc: reranker, content-classifier, stealth-crawler,
  proxy-manager, media-search, fastClassifier, language detection
- New web-svc widgets: KnowledgeCard, ProductCard, ProfileCard, VideoCard,
  UnifiedCard, CardGallery, InlineImageGallery, SourcesPanel, RelatedQuestions
- Improved discover-svc with discover-db integration
- Docker deployment improvements (Caddyfile, vendor.sh, BUILD.md)
- Library-svc: project_id schema migration
- Remove deprecated finance-svc and travel-svc
- Localization improvements across services

Made-with: Cursor

services/auth-svc/Dockerfile

@@ -5,8 +5,8 @@ RUN apk add --no-cache python3 make g++
 WORKDIR /app
 COPY package.json package-lock.json ./
 COPY services/auth-svc/package.json ./services/auth-svc/
-RUN --mount=type=cache,target=/root/.npm \
-    npm ci -w auth-svc
+COPY --from=npm-cache / /tmp/npm-cache
+RUN npm ci -w auth-svc --cache /tmp/npm-cache
 COPY services/auth-svc/tsconfig.json ./services/auth-svc/
 COPY services/auth-svc/src ./services/auth-svc/src
 WORKDIR /app/services/auth-svc
@@ -17,8 +17,8 @@ RUN apk add --no-cache python3 make g++
 WORKDIR /app
 COPY package.json package-lock.json ./
 COPY services/auth-svc/package.json ./services/auth-svc/
-RUN --mount=type=cache,target=/root/.npm \
-    npm ci -w auth-svc --omit=dev
+COPY --from=npm-cache / /tmp/npm-cache
+RUN npm ci -w auth-svc --omit=dev --cache /tmp/npm-cache
 COPY --from=builder /app/services/auth-svc/dist ./services/auth-svc/dist
 WORKDIR /app/services/auth-svc
 EXPOSE 3014