feat: Introduce @automaker/prompts package for AI prompt templates

Changes:
- Added a new package, @automaker/prompts, containing AI prompt templates for enhancing user-written task descriptions.
- Implemented four enhancement modes: improve, technical, simplify, and acceptance, each with corresponding system prompts and examples.
- Updated relevant packages to utilize the new prompts package, ensuring backward compatibility with existing imports.
- Enhanced documentation to include usage examples and integration details for the new prompts.

Benefits:
✅ Streamlined AI prompt management across the codebase
✅ Improved clarity and usability for AI-powered features
✅ Comprehensive documentation for developers

All tests passing.

libs/prompts/src/index.ts

@@ -0,0 +1,25 @@
+/**
+ * @automaker/prompts
+ * AI prompt templates for AutoMaker
+ */
+
+// Enhancement prompts
+export {
+  IMPROVE_SYSTEM_PROMPT,
+  TECHNICAL_SYSTEM_PROMPT,
+  SIMPLIFY_SYSTEM_PROMPT,
+  ACCEPTANCE_SYSTEM_PROMPT,
+  IMPROVE_EXAMPLES,
+  TECHNICAL_EXAMPLES,
+  SIMPLIFY_EXAMPLES,
+  ACCEPTANCE_EXAMPLES,
+  getEnhancementPrompt,
+  getSystemPrompt,
+  getExamples,
+  buildUserPrompt,
+  isValidEnhancementMode,
+  getAvailableEnhancementModes,
+} from './enhancement.js';
+
+// Re-export types from @automaker/types
+export type { EnhancementMode, EnhancementExample } from '@automaker/types';