feat(ai): add Xiaomi MiMo provider (#4005)

* fix(ai): include minimax-cn in cross-provider-handoff matrix

* feat(ai): add Xiaomi MiMo provider

Adds Xiaomi MiMo as an openai-completions-compatible provider.

- packages/ai: register provider in types/KnownProvider, env-api-keys (XIAOMI_API_KEY), generate-models, models.generated.ts, overflow util, README, CHANGELOG
- packages/ai/test: extend stream, tokens, abort, empty, context-overflow, overflow, image-tool-result, tool-call-without-result, total-tokens, unicode-surrogate, cross-provider-handoff matrices with Xiaomi
- packages/coding-agent: default model (mimo-v2.5-pro), display name (Xiaomi MiMo), CLI env var docs, README, docs/providers.md

closes #3912

---------

Co-authored-by: Mario Zechner <badlogicgames@gmail.com>

packages/ai/test/abort.test.ts

@@ -190,6 +190,18 @@ describe("AI Providers Abort Tests", () => {
 		});
 	});
 
+	describe.skipIf(!process.env.XIAOMI_API_KEY)("Xiaomi MiMo Provider Abort", () => {
+		const llm = getModel("xiaomi", "mimo-v2.5-pro");
+
+		it("should abort mid-stream", { retry: 3 }, async () => {
+			await testAbortSignal(llm);
+		});
+
+		it("should handle immediate abort", { retry: 3 }, async () => {
+			await testImmediateAbort(llm);
+		});
+	});
+
 	describe.skipIf(!process.env.KIMI_API_KEY)("Kimi For Coding Provider Abort", () => {
 		const llm = getModel("kimi-coding", "kimi-k2-thinking");