feat: complete Groq provider integration and add Kimi K2 model (#978)

* feat: complete Groq provider integration and add Kimi K2 model

- Add missing getRequiredApiKeyName() method to GroqProvider class
- Register GroqProvider in ai-services-unified.js PROVIDERS object
- Add Groq API key handling to config-manager.js (isApiKeySet and getMcpApiKeyStatus)
- Add GROQ_API_KEY to env.example with format hint
- Add moonshotai/kimi-k2-instruct model to Groq provider ($1/$3 per 1M tokens, 16k max)
- Fix import sorting for linting compliance
- Add GroqProvider mock to ai-services-unified tests

Fixes missing implementation pieces that prevented Groq provider from working.

* chore: improve changeset

---------

Co-authored-by: Ben Vargas <ben@example.com>
Co-authored-by: Ralph Khreish <35776126+Crunchyman-ralph@users.noreply.github.com>

tests/unit/ai-services-unified.test.js

@@ -177,6 +177,13 @@ jest.unstable_mockModule('../../src/ai-providers/index.js', () => ({
 		getRequiredApiKeyName: jest.fn(() => 'XAI_API_KEY'),
 		isRequiredApiKey: jest.fn(() => true)
 	})),
+	GroqProvider: jest.fn(() => ({
+		generateText: jest.fn(),
+		streamText: jest.fn(),
+		generateObject: jest.fn(),
+		getRequiredApiKeyName: jest.fn(() => 'GROQ_API_KEY'),
+		isRequiredApiKey: jest.fn(() => true)
+	})),
 	OpenRouterAIProvider: jest.fn(() => ({
 		generateText: jest.fn(),
 		streamText: jest.fn(),