feat(02-01): AI package foundation — types, interface, mock, prompts, config extension
- internal/ai/types.go: IntakeRequest, IntakeResult, TierConfig, AIConfig domain types
- internal/ai/client.go: AIClient interface + TierClient (go-openai, BaseURL tier-routing)
- internal/ai/mock.go: MockAIClient test double with HighConfidenceResult/LowConfidenceResult fixtures
- internal/ai/prompts/intake.go: BuildIntakePrompt() JSON-extraction prompt template
- internal/config/config.go: Config.AI AIConfig field, tier defaults, env bindings, ai_config.json merge
- ai_config.json: template config with placeholder Tier2 API key
- .gitignore: add ai_config.local.json pattern for real keys (T-02-01 mitigation)
- All tests pass: TestMockAIClient, TestMockAIClientError, TestTierClientConstruction, TestAIConfigDefaults
Mikkel Georgsen
8c03780230