Stabilize recommendation fallback metadata and small runtime/front-end fixes

[SHREESHANTH99]

Motivation

• Make recommendation fallback behavior deterministic and merge-safe by deriving fallback_source from internal metadata instead of brittle human-readable text.
• Ensure endpoints and socket/user handling remain robust after prior merge edits by normalizing IDs and timeouts across backend and frontend.

Description

• Refactor backend/src/routes/recommendationRoutes.js to resolve multiple env names into PYTHON_RECOMMEND_API_URL and PYTHON_HEALTH_URL, add REQUEST_TIMEOUT_MS, a static STATIC_FALLBACK_RECOMMENDATIONS list, Jikan/popular fallbacks, and tag fallback items with _fallbackSource while adding extractFallbackSource and sanitizeFallbackItems helpers to derive fallback_source and remove internal fields before responses.
• Update recommendation endpoints to use verifyToken, compute effectiveUserId, return source/fallback_source consistently, and use the helpers when falling back to static/Jikan data.
• Apply a set of runtime/frontend fixes including: normalize socket user.id vs _id lookup in backend/server.js and SocketContext.jsx, add alt attribute in Navbar.jsx, fix cube scaling in ThreeScene.jsx, stabilize hooks and request handling in SimilarAnime.jsx, AIRecommendations.jsx, ResetPassword.jsx, AuthContext.jsx (exchange token shape and profile resolution), and switch many local API URLs to the 5001 backend port.
• Minor adjustments: set build script to GENERATE_SOURCEMAP=false react-scripts build, remove internal metadata from API outputs, and add small eslint-disable comments where necessary to avoid noisy hook warnings.

Testing

• Ran node --check backend/src/routes/recommendationRoutes.js and it passed syntax validation (success).
• Ran npm run build (GENERATE_SOURCEMAP=false react-scripts build) and the frontend production build completed successfully (compiled assets produced).

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Project	Deployment	Actions	Updated (UTC)
animatch	Ready	Preview, Comment	Feb 23, 2026 0:03am

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