feat(provider): add vercel to all gateway-supported fallback entries

Adds vercel to every fallback entry where the model exists on the
gateway (kimi-k2.5, glm-5, glm-4.6v, minimax-m2.7, grok-code-fast-1,
gpt-5-nano). Adds inferSubProvider mappings for minimax, moonshotai,
and zai. Updates librarian/explore special cases to prefer minimax
via gateway over claude-haiku.

src/cli/provider-model-id-transform.test.ts

@@ -274,6 +274,33 @@ describe("transformModelForProvider", () => {
 			expect(result).toBe("anthropic/claude-opus-4.6")
 		})
 
+		test("prepends minimax/ for minimax models", () => {
+			// #given vercel provider and minimax-m2.7 model
+			// #when transformModelForProvider is called
+			const result = transformModelForProvider("vercel", "minimax-m2.7")
+
+			// #then should produce minimax/minimax-m2.7
+			expect(result).toBe("minimax/minimax-m2.7")
+		})
+
+		test("prepends moonshotai/ for kimi models", () => {
+			// #given vercel provider and kimi-k2.5 model
+			// #when transformModelForProvider is called
+			const result = transformModelForProvider("vercel", "kimi-k2.5")
+
+			// #then should produce moonshotai/kimi-k2.5
+			expect(result).toBe("moonshotai/kimi-k2.5")
+		})
+
+		test("prepends zai/ for glm models", () => {
+			// #given vercel provider and glm-5 model
+			// #when transformModelForProvider is called
+			const result = transformModelForProvider("vercel", "glm-5")
+
+			// #then should produce zai/glm-5
+			expect(result).toBe("zai/glm-5")
+		})
+
 		test("passes through unknown models without sub-provider prefix", () => {
 			// #given vercel provider and an unknown model name
 			// #when transformModelForProvider is called