A run says whether the dashboard, the CLI or a script asked for it

`POST /runs/flows/{name}` hardcoded `cause: "api"`, so every row in the
history claimed the same origin. The body now carries an optional `cause`,
closed to the values the column knows — the dashboard sends nothing and stays
"api", `fluksio run` says "cli", and the SDK client says "sdk".

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013Gf7WaExcJ9bs3kfJXB3nK

docs/code/api.md

@@ -102,7 +102,7 @@ published to. Flows own the namespace; everything else is a client of it.
 
 | Method | Path | What |
 |---|---|---|
-| `POST` | `/runs/flows/{name}` | queue one run — `{"params": {...}, "seed": 7, "draft": false, "no_cache": false}` |
+| `POST` | `/runs/flows/{name}` | queue one run — `{"params": {...}, "seed": 7, "draft": false, "no_cache": false}`. `"cause"` says where it came from — `api` (the default), `cli` or `sdk` |
 | `POST` | `/runs/flows/{name}/sweep` | queue many, sharing a `group_id` |
 | `GET` | `/runs` | the queryable history: `?flow=`, `?status=`, `?group=`, `?digest=`, `?limit=`, `?offset=` |
 | `GET` | `/runs/overview` | one row per flow that has runs, with how many are running or queued |