Phase 4: Dioxus frontend with dataset browser and SQL query editor

- ui: Dioxus WASM app with dataset sidebar, SQL editor (Ctrl+Enter), results table
- ui: dynamic API base URL (same-origin for nginx, port-based for local dev)
- gateway: CORS enabled for cross-origin requests
- nginx: lakehouse.devop.live proxies UI (:3300) + API (:3100) on same origin
- justfile: ui-build, ui-serve, sidecar, up commands added

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/PHASES.md

@@ -40,12 +40,13 @@
 **Gate: PASSED** — Gateway → aibridge → sidecar → Ollama → real 768d embeddings + generation.
 
 ## Phase 4: Frontend
-- [ ] 4.1 — Dioxus scaffold, WASM build
-- [ ] 4.2 — Dataset browser
-- [ ] 4.3 — Query editor + results table
-- [ ] 4.4 — Error display + loading states
+- [x] 4.1 — Dioxus scaffold, WASM build (dx build --platform web)
+- [x] 4.2 — Dataset browser (sidebar, click to select, refresh)
+- [x] 4.3 — Query editor + results table (Ctrl+Enter to run, column types, row count)
+- [x] 4.4 — Error display + loading states
+- [x] 4.5 — Nginx proxy (lakehouse.devop.live), same-origin API detection
 
-**Gate:** Browse datasets and query from browser.
+**Gate: PASSED** — Browse datasets and query from browser at lakehouse.devop.live.
 
 ## Phase 5: Hardening
 - [ ] 5.1 — Proto definitions