Expand search coverage and preview parsing

TODO.md

@@ -340,6 +340,24 @@
 - [x] local `/api/upload` through `scripts/selftest.sh`
 - [ ] full browser-level validation was not fully reproducible in this environment
 
+## Recent Change Log
+- Date: `2026-03-16`
+- What changed:
+  - Increased collector result caps and widened source-specific search query templates for Envato, Artgrid, and Google Video.
+  - Strengthened Gemini query-expansion and vision prompts with a professional video-editor framing.
+  - Restored result modal media fallback so Google Video uses YouTube embed while Envato and Artgrid can show preview video or thumbnail instead of blocked iframe pages.
+  - Expanded generic preview URL parsing so HTML-embedded `.mp4` and `.m3u8` sources are accepted more broadly.
+- Why it changed:
+  - Search result volume was too low.
+  - The user wanted Gemini to reason more like a professional editor.
+  - Envato iframe pages were being refused, Google Video modal opening was broken, and preview extraction still missed known media URLs.
+- How it was verified:
+  - local code inspection against attached Envato / Artgrid HTML samples
+  - `go test ./...`
+- What is still risky or incomplete:
+  - The attached Artgrid HTML sample is a generic homepage shell, so preview extraction still depends on what the live clip page or downstream assets expose at runtime.
+  - Some providers can still refuse iframe rendering even when Artgrid pages currently appear to work.
+
 ## Unraid / Docker / CI Notes
 - Dockerfile uses:
   - Go build stage