docs: organize tool pages by modality under /tools/<modality>/

Move all 157 tool pages into image/video/audio/pdf/data subfolders so URLs read /tools/<modality>/<id> (e.g. /tools/image/crop). Nest the image sub-categories under an Image group in the sidebar so the nav reads by modality. Add public/_redirects (301, clean + .html forms) mapping every old flat /tools/<id> URL to its new path so inbound links keep working. Rewrite all internal /tools links. Verified with a clean docs build (no dead links).

apps/docs/tools/video/resize-video.md

@@ -0,0 +1,58 @@
+---
+description: Scale a video to a new resolution or preset size.
+---
+
+# Resize Video
+
+Scale a video to a new resolution using custom pixel dimensions or a standard preset.
+
+## API Endpoint
+
+`POST /api/v1/tools/video/resize-video`
+
+Accepts multipart form data with a video file and a JSON `settings` field.
+
+## Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| width | integer | No | - | Target width in pixels (16-7680) |
+| height | integer | No | - | Target height in pixels (16-4320) |
+| preset | string | No | `"custom"` | Resolution preset: `custom`, `2160p`, `1440p`, `1080p`, `720p`, `480p`, `360p` |
+
+When `preset` is `"custom"`, at least one of `width` or `height` must be provided. The other dimension scales proportionally.
+
+## Example Request
+
+```bash
+curl -X POST http://localhost:1349/api/v1/tools/video/resize-video \
+  -H "Authorization: Bearer si_your-api-key" \
+  -F "file=@clip.mp4" \
+  -F 'settings={"preset": "720p"}'
+```
+
+Resize to custom dimensions:
+
+```bash
+curl -X POST http://localhost:1349/api/v1/tools/video/resize-video \
+  -H "Authorization: Bearer si_your-api-key" \
+  -F "file=@clip.mp4" \
+  -F 'settings={"width": 1280, "height": 720}'
+```
+
+## Example Response
+
+```json
+{
+  "jobId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+  "downloadUrl": "/api/v1/download/a1b2c3d4-e5f6-7890-abcd-ef1234567890/clip.mp4",
+  "originalSize": 25000000,
+  "processedSize": 8500000
+}
+```
+
+## Notes
+
+- Preset values map to standard heights (e.g. `720p` = 1280x720, `1080p` = 1920x1080). Width scales proportionally from the source aspect ratio.
+- Dimensions are rounded to even numbers as required by most video codecs.
+- Maximum supported resolution is 7680x4320 (8K UHD).