Add local self-test flow and fix fallback regressions

TODO.md

@@ -1,5 +1,43 @@
 # AI Media Hub Handover
 
+## Working Rule
+- From this point on, every meaningful change should be appended to this file so the next handoff can reconstruct:
+  - what changed
+  - why it changed
+  - how it was verified
+  - what remains risky
+- Treat this file as both backlog and handover log, not just a static TODO list.
+
+## Current Session Update (2026-03-13)
+- Added a local self-test workflow before push/container build:
+  - `scripts/selftest.sh`
+  - `scripts/mock_searxng.py`
+- Fixed Korean query translation fallback behavior:
+  - If `GEMINI_API_KEY` is missing or Gemini translation fails, the code now still attempts Google Translate fallback.
+  - If Google Translate fallback fails, dictionary replacement fallback still runs.
+- Added Go tests for translation fallback logic.
+- Fixed frontend HLS preview wiring:
+  - `hls.js` is now loaded in `frontend/index.html`
+  - frontend now tries `hls.js` first, then native HLS playback if available
+- Corrected the practical local verification note:
+  - `go build ./backend` from repo root conflicts with the existing `backend/` directory name
+  - verified build command is now treated as `go build -o /tmp/... ./backend`
+
+## Local Self-Test Workflow
+- Primary command:
+  - `bash scripts/selftest.sh`
+- What it currently verifies:
+  - Go formatting for touched backend files
+  - Python syntax for worker + mock SearXNG
+  - `go test ./...`
+  - backend binary build
+  - local app boot with temp SQLite/download dirs
+  - `/healthz`
+  - `/api/search` using a local mock SearXNG server
+  - `/api/upload`
+- Purpose:
+  - allow safe local regression checks before push or container build without depending on real SearXNG, Gemini, or browser interaction
+
 ## Project Summary
 - Project: `ai-media-hub`
 - Goal: AI-assisted media discovery + ingest dashboard for Unraid
@@ -106,6 +144,8 @@
 - Search relevance is still not considered stable enough.
 - Gemini batch evaluation exists, but search quality can still degrade if upstream SearXNG results are noisy.
 - Frontend JavaScript was not linted with Node tooling in this environment because `node` is not installed here.
+- Full browser-level preview validation is still not covered by the local self-test script.
+- Search cards still render recommendation reason text, not a robust asset description/snippet mapping.
 
 ## Frontend Debug Logger
 - UI button: bottom-right `Logs`
@@ -173,12 +213,17 @@
 - [ ] Envato / Artgrid preview extraction hardening
 - [ ] Search result relevance validation against real user queries
 - [ ] Better matching between rendered description and actual linked asset
+- [ ] Add browser-level verification for preview/HLS behavior
+- [ ] Add more automated coverage for search ranking / filtering logic
 - [ ] Add proper frontend build/lint step if Node becomes available
 
 ## Verified Locally In This Environment
-- [x] `go build ./backend`
-- [x] Python syntax check for worker at various stages
-- [x] basic server boot / `/healthz` at various stages
+- [x] `go build -o /tmp/ai-media-hub ./backend`
+- [x] `go test ./...` (currently no broad test suite beyond the added fallback tests)
+- [x] Python syntax check for worker + self-test helper
+- [x] local app boot / `/healthz` through `scripts/selftest.sh`
+- [x] local `/api/search` against mock SearXNG through `scripts/selftest.sh`
+- [x] local `/api/upload` through `scripts/selftest.sh`
 - [ ] full browser-level validation was not fully reproducible in this environment
 
 ## Short Handover Summary