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/images-to-video.md

@@ -0,0 +1,51 @@
+---
+description: Turn a set of images into a slideshow video.
+---
+
+# Images to Video
+
+Turn a set of images into a slideshow video with configurable duration per image, resolution, and frame rate.
+
+## API Endpoint
+
+`POST /api/v1/tools/video/images-to-video`
+
+Accepts multipart form data with two or more image files and a JSON `settings` field.
+
+## Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| secondsPerImage | number | No | `2` | Display duration per image in seconds (0.5-10) |
+| resolution | string | No | `"720p"` | Output resolution: `1080p`, `720p`, `square` |
+| fps | integer | No | `30` | Output frame rate (10-60) |
+
+## Example Request
+
+```bash
+curl -X POST http://localhost:1349/api/v1/tools/video/images-to-video \
+  -H "Authorization: Bearer si_your-api-key" \
+  -F "file=@slide1.jpg" \
+  -F "file=@slide2.jpg" \
+  -F "file=@slide3.jpg" \
+  -F "file=@slide4.jpg" \
+  -F 'settings={"secondsPerImage": 3, "resolution": "1080p"}'
+```
+
+## Example Response
+
+```json
+{
+  "jobId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+  "downloadUrl": "/api/v1/download/a1b2c3d4-e5f6-7890-abcd-ef1234567890/slideshow.mp4",
+  "originalSize": 3500000,
+  "processedSize": 1200000
+}
+```
+
+## Notes
+
+- Accepts 2-60 image files per request. Images appear in the video in upload order.
+- Images are resized and padded to fit the target resolution while preserving aspect ratio.
+- The `square` resolution option produces a 720x720 video, useful for social media.
+- Output format is always MP4 (H.264).