feat(embeds): geo/gpx/3D/YouTube/media keyword system + docs, sanitized mirrors

- new snippet geo_map_render.js: [map] inline geomaps (tree order, tint,
  theme-following), [gpx] stats card + elevation profile with hover cursor
  (km from start, d-height, vertical guide), [yt] privacy click-to-load
  facade, [video]/[audio] inline players fed from the new geoData indexes
- 3d_model_viewer.js: [cad] keyword + title/ID resolution via geoData.cad,
  sizes/captions, real occt-wasm ESM pair (fixes 'STEP worker error'),
  code-span-safe keyword scan (docs can show examples)
- blog_generator.js: buildGeoData() v6 – maps (geolocation + geoShape
  point/line/polygon + child GPX tracks), gpx/cad/media indexes,
  branch-change rebuild for route reordering
- generated/geo_data.js placeholder; docs/embed-keywords.md (new) +
  embed-3d-model Option D; README layout/wiring/notes tables updated
- license: runtime components (MapLibre ISC, VersaTiles MIT/ODbL, YouTube)
- hygiene: removed leaked note IDs and instance domain from theme docs

THIRD_PARTY_LICENSES.md

@@ -23,6 +23,17 @@ The following files in this repository are **not** covered by the GPL-3.0 and ke
 | `lib/3d/occt-wasm-bundle.js`, `lib/3d/occt-wasm.wasm` | [occt-wasm](https://github.com/andymai/occt-wasm) (OpenCASCADE **OCCT V8**, WebAssembly, esbuild-bundled `OcctKernel`) | [MIT OR Apache-2.0](#mit-license) |
 | `scripts/bmc_button.js` | embeds the Trilium logo (SVG) from [Trilium/TriliumNext](https://github.com/TriliumNext/Trilium) | [AGPL-3.0](https://www.gnu.org/licenses/agpl-3.0.txt) |
 
+## Runtime components (loaded from CDNs at page runtime, not vendored)
+
+These are referenced by `scripts/geo_map_render.js` and `scripts/3d_model_viewer.js`
+and fetched by the browser when a page renders — they are **not** stored in this repository:
+
+| Component | Source | License |
+|---|---|---|
+| MapLibre GL JS 4.7.1 (map rendering, from `unpkg.com`) | [maplibre/maplibre-gl-js](https://github.com/maplibre/maplibre-gl-js) | ISC |
+| VersaTiles basemap style & vector tiles (`muted`, from `tiles.versatiles.org`) | [versamaps](https://github.com/versamaps) | style: MIT · tile data: © [OpenStreetMap](https://www.openstreetmap.org/copyright) contributors (ODbL) |
+| YouTube click-to-load facade (thumbnail `i.ytimg.com`, player `youtube-nocookie.com` after user click) | YouTube | no vendored code; subject to YouTube ToS |
+
 ## BSD-3-Clause
 
 ```