refactor: Remove semantic search and vector embedding functionality

Removes @xenova/transformers dependency, vector storage tables, embedding generation, and semantic search APIs. Simplifies context building to use only FTS search. Eliminates visualizer server, postinstall model download, and related CLI commands. Reduces package size and complexity while maintaining core static analysis capabilities.

src/db/queries.ts

@@ -1290,7 +1290,6 @@ export class QueryBuilder {
     this.nodeCache.clear();
     this.db.transaction(() => {
       this.db.exec('DELETE FROM unresolved_refs');
-      this.db.exec('DELETE FROM vectors');
       this.db.exec('DELETE FROM edges');
       this.db.exec('DELETE FROM nodes');
       this.db.exec('DELETE FROM files');