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/color-blindness.md

@@ -0,0 +1,59 @@
+---
+description: Simulate how images appear to people with different types of color vision deficiency.
+---
+
+# Color Blindness Simulation
+
+Simulate color vision deficiency (CVD) to preview how images appear to people with various types of color blindness. Useful for accessibility testing of designs, charts, and UI.
+
+## API Endpoint
+
+`POST /api/v1/tools/color-blindness`
+
+Accepts multipart form data with an image file and a JSON `settings` field.
+
+## Parameters
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| simulationType | string | No | `"deuteranomaly"` | Type of color vision deficiency to simulate |
+
+### Simulation Types
+
+| Value | Condition | Description |
+|-------|-----------|-------------|
+| `protanopia` | Red-blind | Complete absence of red cone cells |
+| `deuteranopia` | Green-blind | Complete absence of green cone cells |
+| `tritanopia` | Blue-blind | Complete absence of blue cone cells |
+| `protanomaly` | Red-weak | Reduced red cone sensitivity |
+| `deuteranomaly` | Green-weak | Reduced green cone sensitivity (most common) |
+| `tritanomaly` | Blue-weak | Reduced blue cone sensitivity |
+| `achromatopsia` | Total color blind | Complete absence of color vision |
+| `blueConeMonochromacy` | Blue-cone only | Only blue cones functional |
+
+## Example Request
+
+```bash
+curl -X POST http://localhost:1349/api/v1/tools/color-blindness \
+  -H "Authorization: Bearer si_your-api-key" \
+  -F "file=@design.png" \
+  -F 'settings={"simulationType": "deuteranopia"}'
+```
+
+## Example Response
+
+```json
+{
+  "jobId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+  "downloadUrl": "/api/v1/download/a1b2c3d4-e5f6-7890-abcd-ef1234567890/design.png",
+  "originalSize": 1850000,
+  "processedSize": 1820000
+}
+```
+
+## Notes
+
+- Deuteranomaly (green-weak) is the default because it is the most common form of color vision deficiency, affecting approximately 6% of males.
+- The simulation uses color transformation matrices that model how reduced or absent cone photoreceptors alter perceived colors.
+- This tool is non-destructive and produces a preview only. It does not modify the original image for accessibility.
+- Output format matches the input format. HEIC, RAW, PSD, and SVG inputs are automatically decoded before processing.