feat: add developer docs links (docs, reference, guides)

README.md

@@ -171,8 +171,47 @@ row in the leaderboard:
 
 In other words: **this dataset is also a benchmark of StemSplit's own
 quality**. We didn't add a separate `stemsplit_api` row because it would
-just duplicate those numbers. If you'd rather not stand up Demucs, ffmpeg,
-torchcodec, and a GPU yourself: → [stemsplit.io](https://stemsplit.io).
+just duplicate those numbers.
+
+---
+
+## Use the StemSplit API
+
+If you'd rather not stand up Demucs, ffmpeg, torchcodec, and a GPU yourself,
+the StemSplit API ships the same models with a single HTTP call. Pricing,
+quotas, and the full feature set are documented in our developer portal:
+
+| Resource | URL |
+|---|---|
+| 🏠 Developer landing | [stemsplit.io/developers](https://stemsplit.io/developers) |
+| 📘 Getting-started docs (auth, upload, polling) | [stemsplit.io/developers/docs](https://stemsplit.io/developers/docs) |
+| 📑 API reference (every endpoint, every field) | [stemsplit.io/developers/reference](https://stemsplit.io/developers/reference) |
+| 🧩 Integration guides (Zapier, n8n, Make, Pipedream, Discord, Audacity, DJ workflows, ...) | [stemsplit.io/developers/guides](https://stemsplit.io/developers/guides) |
+
+Minimal example — submit a job, poll, download stems:
+
+```bash
+# 1. Submit
+JOB=$(curl -sS -X POST https://stemsplit.io/api/v1/jobs \
+  -H "Authorization: Bearer $STEMSPLIT_API_KEY" \
+  -F "file=@song.wav" \
+  -F "stems=4")
+JOB_ID=$(echo "$JOB" | jq -r .id)
+
+# 2. Poll until completed
+while [ "$(curl -sS https://stemsplit.io/api/v1/jobs/$JOB_ID \
+  -H "Authorization: Bearer $STEMSPLIT_API_KEY" | jq -r .status)" != "completed" ]; do
+  sleep 3
+done
+
+# 3. Download every stem
+curl -sS https://stemsplit.io/api/v1/jobs/$JOB_ID \
+  -H "Authorization: Bearer $STEMSPLIT_API_KEY" \
+  | jq -r '.stems | to_entries[] | "\(.key) \(.value)"' \
+  | while read stem url; do curl -sSL "$url" -o "$stem.wav"; done
+```
+
+→ Get an API key at [stemsplit.io/developers](https://stemsplit.io/developers).
 
 ---
 
@@ -217,14 +256,13 @@ PyTorch 2.11 with the MPS backend, for the v1 lineup:
 
 We run [StemSplit](https://stemsplit.io) — a hosted stem-separation service —
 and we needed an honest, public, reproducible way to compare ourselves to the
-state of the art. So we open-sourced it. If you want to ship a separation
-product without standing up GPU infrastructure, our API is a drop-in:
+state of the art. So we open-sourced it.
 
-```bash
-curl -X POST https://stemsplit.io/api/v1/jobs \
-  -H "Authorization: Bearer $YOUR_KEY" \
-  -F "file=@song.wav" -F "stems=4"
-```
+Want to ship a separation product without standing up GPU infrastructure?
+The same models are one HTTP call away — see the
+[Use the StemSplit API](#use-the-stemsplit-api) section above, or jump
+straight to the [developer docs](https://stemsplit.io/developers/docs)
+and [API reference](https://stemsplit.io/developers/reference).
 
 ---