docs: clarify caching as future enhancement

Update ARCHITECTURE.md to clearly indicate that caching mechanisms
(AST, CFG, LSH caching) are planned for future releases and not yet
implemented in v1.0.0. This ensures documentation accurately reflects
the current implementation state.

docs/ARCHITECTURE.md

@@ -562,14 +562,18 @@ type LSHConfig struct {
 - Use object pools for frequent allocations
 - Memory-aware batch processing
 
-### 4. Caching
+### 4. Caching (Future Enhancement)
 
+**Note: Caching is not yet implemented in v1.0.0. This section describes the planned architecture for future releases.**
+
+Planned caching features:
 - Cache parsed ASTs for unchanged files
 - Store CFGs for incremental analysis
 - Memoize APTED distance calculations
 - LSH signature caching
 
 ```go
+// Planned implementation (not yet available)
 type Cache struct {
     ast       map[string]*AST      // File hash → AST
     cfg       map[string]*CFG      // Function → CFG