feat: add per-provider, model index, and schema API endpoints

[wojons]

Summary

Add three new lightweight API endpoints to models.dev — a model index, per-provider data, and a JSON Schema — making the data more accessible for AI agents without requiring a full 1.8 MB download.

New Endpoints

Endpoint	Size	Description
/api/models.json	~509 KB	Model ID → providers list + capabilities (tool_call, reasoning, modalities, open_weights)
/api/{provider}.json	0.6–209 KB each	Full data for a single provider (120 files)
/api/schema.json	~14 KB	JSON Schema describing the full data shape

Usage

# Find which providers offer a specific model
curl -s https://models.dev/api/models.json | jq '."claude-sonnet-4-5".providers'
# Get full pricing/details for one provider
curl -s https://models.dev/api/anthropic.json | jq '.anthropic.models["claude-sonnet-4-5"].cost'
# Validate data structure
curl -s https://models.dev/api/schema.json
Implementation
Build (packages/web/script/build.ts):
- After the existing _api.json is generated, also writes per-provider _api/{provider}.json files
- Builds a reverse model index (_api/models.json) by iterating all providers and grouping models by their model ID
- Generates a JSON Schema (_api/schema.json) from the Provider and Model shapes
Worker (packages/function/src/worker.ts):
- Routes /api/models.json → /_api/models.json
- Routes /api/schema.json → /_api/schema.json
- Routes /api/{provider}.json → /_api/{provider}.json (regex match on ^/api/[a-z0-9][a-z0-9._-]+\.json$)
Documentation:
- "How to use" modal on the site updated with sections and curl examples for all new endpoints
- README updated with endpoints table and usage examples
Notes
- The model index is ~1/3 the size of the full API (509 KB vs 1.8 MB)
- Name mismatch warnings are printed during build when different providers give the same model ID different display names (pre-existing data inconsistency, not introduced here)
- No new dependencies added
- Existing bun validate flow is unaffected since the new files derive from the same generate() output