docs: add per-tool API documentation and fix parity gaps

- Create 53 per-tool VitePress documentation pages with accurate
  parameters from Zod schemas, example requests, and response formats
- Add root llms.txt for LLM-friendly repo browsing
- Fix OpenAPI spec: add auth and 422 error schemas to
  edit-metadata/inspect and strip-metadata/inspect sub-routes
- Fix tool count inconsistency (52 -> 53) across landing site,
  e2e tests, and local docs
- Rename color-adjustments.ts to adjust-colors.ts to match tool ID
- Update VitePress sidebar with all 8 tool categories and top nav

apps/docs/tools/info.md

@@ -0,0 +1,89 @@
+---
+description: View detailed image metadata, properties, and per-channel histogram statistics.
+---
+
+# Image Info
+
+Read-only analysis tool that returns comprehensive image metadata including dimensions, format, color space, EXIF/ICC/XMP presence, and per-channel histogram statistics. Does not produce a processed output file.
+
+## API Endpoint
+
+`POST /api/v1/tools/info`
+
+Accepts multipart form data with an image file. No settings field is needed.
+
+## Parameters
+
+This tool has no configurable parameters. Simply upload the image file.
+
+| Field | Type | Required | Description |
+|-------|------|----------|-------------|
+| file | file | Yes | The image to analyze |
+
+## Example Request
+
+```bash
+curl -X POST http://localhost:1349/api/v1/tools/info \
+  -H "Authorization: Bearer si_your-api-key" \
+  -F "file=@photo.jpg"
+```
+
+## Example Response
+
+```json
+{
+  "filename": "photo.jpg",
+  "fileSize": 2450000,
+  "width": 4032,
+  "height": 3024,
+  "format": "jpeg",
+  "channels": 3,
+  "hasAlpha": false,
+  "colorSpace": "srgb",
+  "density": 72,
+  "isProgressive": false,
+  "orientation": 1,
+  "hasProfile": true,
+  "hasExif": true,
+  "hasIcc": true,
+  "hasXmp": false,
+  "bitDepth": "8",
+  "pages": 1,
+  "histogram": [
+    { "channel": "red", "min": 0, "max": 255, "mean": 128.45, "stdev": 52.31 },
+    { "channel": "green", "min": 2, "max": 253, "mean": 115.22, "stdev": 48.76 },
+    { "channel": "blue", "min": 0, "max": 250, "mean": 102.89, "stdev": 55.14 }
+  ]
+}
+```
+
+## Response Fields
+
+| Field | Type | Description |
+|-------|------|-------------|
+| filename | string | Sanitized filename |
+| fileSize | number | File size in bytes |
+| width | number | Image width in pixels |
+| height | number | Image height in pixels |
+| format | string | Detected format (jpeg, png, webp, etc.) |
+| channels | number | Number of color channels |
+| hasAlpha | boolean | Whether the image has an alpha channel |
+| colorSpace | string | Color space (srgb, cmyk, etc.) |
+| density | number or null | DPI/PPI resolution |
+| isProgressive | boolean | Whether JPEG uses progressive encoding |
+| orientation | number or null | EXIF orientation value (1-8) |
+| hasProfile | boolean | Whether an ICC profile is embedded |
+| hasExif | boolean | Whether EXIF metadata is present |
+| hasIcc | boolean | Whether an ICC color profile is present |
+| hasXmp | boolean | Whether XMP metadata is present |
+| bitDepth | string or null | Bits per sample |
+| pages | number | Number of pages (for multi-page formats like TIFF, GIF) |
+| histogram | array | Per-channel statistics (min, max, mean, standard deviation) |
+
+## Notes
+
+- This is a read-only endpoint. It does not produce a downloadable output file or a `jobId`.
+- For RAW format images (DNG, CR2, NEF, ARW, etc.), ExifTool is used to extract true sensor dimensions and metadata flags that Sharp cannot read directly.
+- HEIC/HEIF files are decoded to PNG internally to extract pixel statistics, since Sharp cannot decode HEVC pixels.
+- The histogram provides min/max/mean/stdev per channel, not a full 256-bin distribution.
+- The `density` field reflects the embedded DPI metadata, if present.