fix: remove hardcoded dimension fallback to respect UI settings

- Remove hardcoded 1536 fallback in getStateToPostToWebview()
- Remove hardcoded fallback in getState()
- Allow undefined dimension to flow through to service layer
- Service layer properly resolves dimension from model profiles or user config

Fixes #5754

Author: roomote

src/core/webview/ClineProvider.ts

@@ -1867,7 +1867,7 @@ export class ClineProvider
 				codebaseIndexEmbedderProvider: codebaseIndexConfig?.codebaseIndexEmbedderProvider ?? "openai",
 				codebaseIndexEmbedderBaseUrl: codebaseIndexConfig?.codebaseIndexEmbedderBaseUrl ?? "",
 				codebaseIndexEmbedderModelId: codebaseIndexConfig?.codebaseIndexEmbedderModelId ?? "",
-				codebaseIndexEmbedderModelDimension: codebaseIndexConfig?.codebaseIndexEmbedderModelDimension ?? 1536,
+				codebaseIndexEmbedderModelDimension: codebaseIndexConfig?.codebaseIndexEmbedderModelDimension,
 				codebaseIndexOpenAiCompatibleBaseUrl: codebaseIndexConfig?.codebaseIndexOpenAiCompatibleBaseUrl,
 				codebaseIndexSearchMaxResults: codebaseIndexConfig?.codebaseIndexSearchMaxResults,
 				codebaseIndexSearchMinScore: codebaseIndexConfig?.codebaseIndexSearchMinScore,