fix(model-heuristics): register Grok family with reasoningEffort support

Grok model IDs (e.g. `grok-4.3`, `grok-3-mini`) were missing from `HEURISTIC_MODEL_FAMILY_REGISTRY`, so `resolveCompatibleModelSettings` returned an "unknown family" result for them.

The `chat.params` hook treats unknown families as "no reasoning support" and deletes `output.options.reasoningEffort` before the request leaves the plugin, so users routing Grok via OpenAI-compatible endpoints never saw their reasoning effort forwarded — even with `forceReasoning: true`.

Add a `grok` family entry that includes any model ID containing "grok", exposes `low | medium | high` variants, and sets `reasoningEfforts` so the heuristic surfaces the same capability flag used by the `chat.params` hook. Extend the family table-driven test in `model-settings-compatibility.test.ts` to cover `grok-4.3`.

src/shared/model-capability-heuristics.ts

@@ -45,6 +45,12 @@ export const HEURISTIC_MODEL_FAMILY_REGISTRY: ReadonlyArray<HeuristicModelFamily
     includes: ["gemini"],
     variants: ["low", "medium", "high"],
   },
+  {
+    family: "grok",
+    includes: ["grok"],
+    variants: ["low", "medium", "high"],
+    reasoningEfforts: ["low", "medium", "high"],
+  },
   {
     family: "kimi-thinking",
     includes: ["kimi-thinking", "k2-thinking", "k2-think"],

src/shared/model-settings-compatibility.test.ts

@@ -253,6 +253,7 @@ describe("resolveCompatibleModelSettings", () => {
       hasReasoningEffort: boolean
     }> = [
       { name: "Gemini", modelID: "gemini-3.1-pro", expectedVariants: ["low", "medium", "high"], hasReasoningEffort: false },
+      { name: "Grok", modelID: "grok-4.3", expectedVariants: ["low", "medium", "high"], hasReasoningEffort: true },
       { name: "Kimi (kimi)", modelID: "kimi-k2.5", expectedVariants: ["low", "medium", "high"], hasReasoningEffort: false },
       { name: "Kimi (k2)", modelID: "k2-v2", expectedVariants: ["low", "medium", "high"], hasReasoningEffort: false },
       { name: "GLM", modelID: "glm-5", expectedVariants: ["low", "medium", "high"], hasReasoningEffort: false },