Close OSS self-host gaps: in-repo API docs, legal notes, and packaging.

Add MIT license and docs/api, strip SaaS status/admin remnants from robots and footer, align env/compose/README with payment-free product truth.

docs/api/overview.md

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+# API overview
+
+Programmatic uploads and batch jobs for self-hosted Songs2VID. Generate your API key under **Dashboard → Settings → API key**.
+
+Keys start with `s2yt_live_` and are shown once at creation. The OSS / Docker image always allows API use — there is no plan, credit, or paywall gate.
+
+There are **no billing endpoints** in this edition.
+
+## Authentication
+
+Send the key on every request:
+
+```http
+Authorization: Bearer s2yt_live_your_key_here
+```
+
+Requirements:
+
+- YouTube channel connected (sign in with Google OAuth that includes YouTube scopes)
+
+OAuth setup: root [README](../../README.md) and Google’s [OAuth 2.0 for Web Server Applications](https://developers.google.com/identity/protocols/oauth2/web-server). YouTube scopes/API: [YouTube Data API Overview](https://developers.google.com/youtube/v3/getting-started).
+
+## Rate limits
+
+Self-hosted OSS uses a very high per-account ceiling (effectively unlimited for normal automation). You will rarely see `429`.
+
+If a limit is hit, the response is **429** with `retryAfterSeconds` and a `Retry-After` header. See [Endpoints — HTTP errors](./endpoints.md#http-errors).
+
+## Choosing a flow
+
+### Recommended: two-step (especially 5+ audio files)
+
+1. Upload each file with `POST /api/v1/upload`
+2. Create the job with `POST /api/v1/jobs` (JSON paths)
+
+This avoids huge multipart bodies. Max batch size is **100** tracks per job.
+
+### One-shot batch: small packs only
+
+`POST /api/v1/jobs/batch` accepts one cover image and a few audio files in a single multipart request. Large bodies often fail with:
+
+```text
+failed to parse body as FormData
+```
+
+Prefer two-step for albums or long tracklists.
+
+## Job lifecycle
+
+1. Create job → status `PENDING`
+2. Worker picks items → `ENCODING` → `UPLOADING` → `COMPLETED` or `FAILED`
+3. Job rolls up to `COMPLETED`, `FAILED`, or `PARTIAL`
+
+Poll with `GET /api/v1/jobs/:id`.
+
+## Discovery
+
+```http
+GET /api/v1
+```
+
+Returns the endpoint list and requirements (no auth). Useful as a machine-readable catalog of what this instance exposes.
+
+## Next
+
+See [Endpoints](./endpoints.md) for curl examples. Hosted HTML docs: [docs.songs2vid.com/docs/api/overview](https://docs.songs2vid.com/docs/api/overview).