[codex] Consolidate backend live snapshot routes

[zifanzhou1024]

Summary

• Consolidates server-rendered frontend data loading so snapshot, experimental, and heatmap pages call FastAPI directly through shared server helpers while browser requests keep using same-origin Next proxy routes.
• Adds a shared FastAPI LiveSnapshotService so snapshot, experimental, heatmap, scenario, and stream routes derive from one cached materialized live snapshot source.
• Preserves Moomoo and IBKR capabilities, including Moomoo heatmap session routing and backend admin-token forwarding in private mode.
• Adds Moomoo dashboard source labeling so compatibility collector data is not shown as IBKR-only.

Root Cause

Server-rendered pages and FastAPI routes were each rebuilding or proxying through separate paths, which added redundant hops and duplicated live snapshot assembly. The dashboard also labeled Moomoo compatibility collector output with IBKR-specific text.

Validation

• pnpm typecheck:web
• pnpm test:web - 447 passed
• pnpm test:api - 295 passed
• pnpm test:contracts - 8 passed
• pnpm test:scripts - 3 passed
• pnpm test:collector - 169 passed
• PYTHONPATH=services/collector:apps/api .venv/bin/pytest services/collector/tests/test_ibkr_config.py -q - 15 passed
• git diff --check
• Localhost smoke: /, /experimental, /heatmap, and Next API routes returned 200 with live Moomoo data