docs: complete the API reference catalog with video/audio/document/data tools (#256)

rest.md and the docs sidebar still listed only image tools. The OpenAPI spec (#254) now covers all 157 tools, but the hand-written reference lagged.

- rest.md: add Video (29), Audio (17), Document (36), and Data (10) tool tables, and add the 12 newer image tools into their existing category tables (168 tool rows total)
- sidebar: add a "Video, Audio, Document & Data" group linking to the new rest.md sections, so the nav reflects all modalities without needing per-tool pages

Docs site builds cleanly (no dead links). Per-tool doc pages for non-image tools are intentionally not generated here; the REST reference + Scalar + /llms.txt cover them.

apps/docs/.vitepress/config.mts

@@ -214,6 +214,15 @@ export default defineConfig({
               { text: "PNG Transparency Fixer", link: "/tools/transparency-fixer" },
             ],
           },
+          {
+            text: "Video, Audio, Document & Data",
+            items: [
+              { text: "Video tools", link: "/api/rest#video-tools" },
+              { text: "Audio tools", link: "/api/rest#audio-tools" },
+              { text: "Document tools", link: "/api/rest#document-tools" },
+              { text: "Data tools", link: "/api/rest#data-tools" },
+            ],
+          },
         ],
       },
       {