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/gif-tools.md

@@ -0,0 +1,140 @@
+# GIF Tools
+
+Resize, optimize, change speed, reverse, extract frames, and rotate animated GIFs. Provides multiple operation modes in a single tool.
+
+## API Endpoint
+
+`POST /api/v1/tools/gif-tools`
+
+## Parameters
+
+### Common Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| mode | string | No | `"resize"` | Operation mode: `resize`, `optimize`, `speed`, `reverse`, `extract`, `rotate` |
+| loop | number | No | 0 | Loop count for output GIF (0 = infinite, 1-100 = finite loops) |
+
+### Resize Mode Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| width | integer | No | - | Target width in pixels (1 to 16384) |
+| height | integer | No | - | Target height in pixels (1 to 16384) |
+| percentage | number | No | - | Scale by percentage (1 to 500). Overrides width/height if set. |
+
+### Optimize Mode Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| colors | number | No | 256 | Maximum number of colors in palette (2 to 256) |
+| dither | number | No | 1.0 | Dithering strength (0 to 1, where 0 disables dithering) |
+| effort | number | No | 7 | Optimization effort level (1 to 10, higher = slower but smaller) |
+
+### Speed Mode Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| speedFactor | number | No | 1.0 | Speed multiplier (0.1 to 10). Values > 1 speed up, < 1 slow down. |
+
+### Extract Mode Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| extractMode | string | No | `"single"` | Extraction mode: `single`, `range`, `all` |
+| frameNumber | number | No | 0 | Frame index to extract in `single` mode (0-based) |
+| frameStart | number | No | 0 | Start frame index for `range` mode (0-based) |
+| frameEnd | number | No | - | End frame index for `range` mode (0-based, inclusive) |
+| extractFormat | string | No | `"png"` | Format for extracted frames: `png`, `webp` |
+
+### Rotate Mode Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| angle | number | No | - | Rotation angle: `90`, `180`, or `270` degrees |
+| flipH | boolean | No | `false` | Flip horizontally |
+| flipV | boolean | No | `false` | Flip vertically |
+
+## Example Requests
+
+### Resize
+
+```bash
+curl -X POST http://localhost:13490/api/v1/tools/gif-tools \
+  -F "file=@animation.gif" \
+  -F 'settings={"mode":"resize","percentage":50}'
+```
+
+### Optimize
+
+```bash
+curl -X POST http://localhost:13490/api/v1/tools/gif-tools \
+  -F "file=@large.gif" \
+  -F 'settings={"mode":"optimize","colors":128,"effort":9}'
+```
+
+### Speed Up
+
+```bash
+curl -X POST http://localhost:13490/api/v1/tools/gif-tools \
+  -F "file=@animation.gif" \
+  -F 'settings={"mode":"speed","speedFactor":2.0}'
+```
+
+### Extract Single Frame
+
+```bash
+curl -X POST http://localhost:13490/api/v1/tools/gif-tools \
+  -F "file=@animation.gif" \
+  -F 'settings={"mode":"extract","extractMode":"single","frameNumber":5,"extractFormat":"png"}'
+```
+
+## Example Response
+
+```json
+{
+  "jobId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+  "downloadUrl": "/api/v1/download/a1b2c3d4-e5f6-7890-abcd-ef1234567890/animation.gif",
+  "originalSize": 2345678,
+  "processedSize": 1234567
+}
+```
+
+## Info Sub-Route
+
+`POST /api/v1/tools/gif-tools/info`
+
+Returns metadata about an animated GIF without processing it.
+
+### Info Request
+
+```bash
+curl -X POST http://localhost:13490/api/v1/tools/gif-tools/info \
+  -F "file=@animation.gif"
+```
+
+### Info Response
+
+```json
+{
+  "width": 480,
+  "height": 320,
+  "pages": 24,
+  "delay": [100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100],
+  "loop": 0,
+  "fileSize": 2345678,
+  "duration": 2400
+}
+```
+
+## Notes
+
+- Uses the standard `createToolRoute` factory for the main processing endpoint.
+- The info endpoint only requires a file upload (no settings needed).
+- In `resize` mode, if `percentage` is provided it takes priority over `width`/`height`. The resize uses `fit: inside` to maintain aspect ratio.
+- In `speed` mode, frame delays are divided by the speed factor. Minimum delay per frame is 20ms (GIF spec limitation).
+- In `reverse` mode, the `speedFactor` parameter is also available to simultaneously adjust speed while reversing.
+- In `extract` mode with `range` or `all`, the output is a ZIP file containing individual frames.
+- In `rotate` mode, each frame is processed individually and reassembled into an animation.
+- The `loop` parameter controls how many times the output GIF loops. Use 0 for infinite looping.
+- The `duration` field in the info response is the total animation duration in milliseconds.