feat(providers): add Cline free-tier models and sync Freebuff catalog

- Cline: 6 free models, cline-cli product headers, API-key auth,
  {data} envelope unwrap, workos: prefix handling
- Freebuff: muse-spark 1.3 → 1.2 (upstream withdrawal 2026-09-07),
  DeepSeek V4.1 Flash rename

open-sse/providers/registry/freebuff.js

@@ -63,7 +63,7 @@ export default {
     usage: true,
   },
   // Mirrors the Freebuff waiting-room picker (upstream FREEBUFF_MODELS) as of
-  // 2026-09-07. NO per-model prices live here: Freebucks pricing is
+  // 2026-09-11. NO per-model prices live here: Freebucks pricing is
   // server-authoritative — the session response's `freebucks` block carries
   // `prices` (model → Freebucks/hr) plus an announced `priceChanges` schedule
   // (promos like Solar Pro 4's Labor Day run expire server-side; see
@@ -78,13 +78,20 @@ export default {
   // only claim while the backend advertises it via limitedModelOffers on the
   // session status (the executor auto-checks before claiming); the model is
   // otherwise refused.
+  // meta/muse-spark-1.3-contributor was withdrawn upstream 2026-09-07 (Meta
+  // returns 404 model_not_found on every key) and replaced in the picker by
+  // meta/muse-spark-1.2-contributor — same Contributor terms/pool. 1.3 is
+  // intentionally NOT listed: 9Router has no server-side coercion, so a dead
+  // pick would only fail.
+  // deepseek/deepseek-v4-flash was RENAMED upstream 2026-09-10 to DeepSeek
+  // V4.1 Flash (same undated wire id, new build) — display label follows.
   models: [
     { id: "z-ai/glm-5.3-flash", name: "GLM 5.3 Flash" },
-    { id: "deepseek/deepseek-v4-flash", name: "DeepSeek V4 Flash" },
+    { id: "deepseek/deepseek-v4-flash", name: "DeepSeek V4.1 Flash" },
     { id: "openai/gpt-5.6-luna", name: "GPT-5.6 Luna" },
     { id: "mimo/mimo-v2.5", name: "MiMo 2.5" },
     { id: "upstage/solar-pro4", name: "Solar Pro 4" },
-    { id: "meta/muse-spark-1.3-contributor", name: "Muse Spark 1.3" },
+    { id: "meta/muse-spark-1.2-contributor", name: "Muse Spark 1.2" },
     { id: "anthropic/claude-fable-5", name: "Claude Fable 5 (limited offer)" },
   ],
   // Login-flow host — the CLI in freebuff mode logs in via freebuff.com, and