Refactor and enhance codebase with various improvements

- Updated `CompactCacheKey` to use `CacheType` for better type safety.
- Added `last_value` method to `MovingAverage` for improved performance monitoring.
- Enhanced `ChangePropagationManager` to escalate priority for user-visible changes.
- Improved `IntelligentFileWatcher` with initial state bootstrap and better event handling.
- Added `generate_text_embedding` method to `EmbeddingGenerator` for direct text embeddings.
- Updated API documentation to reflect upcoming SDK availability and command-line usage.
- Enhanced symbol extraction and import resolution in various languages.
- Improved error handling and performance in file watching and change detection.

Author: jruokola

Cargo.lock

@@ -119,7 +119,7 @@ async-graphql = "7.0"
 async-graphql-axum = "7.0"
 
 # Web framework
-axum = "0.7"
+axum = "0.8"
 tower = "0.4"
 tower-http = "0.5"
 hyper = "1.0"