Fix path metadata consistency in incremental vector store updates

Prepend "./" to file paths passed to SimpleDirectoryReader during
incremental updates so source document metadata matches full rebuilds.
Also add API_key_temp to .gitignore.

.gitignore

@@ -23,6 +23,7 @@ data
 
 # Secrets
 .env
+API_key_temp
 
 # Query log
 query.log

build_exp_claude.py

@@ -145,7 +145,10 @@ def update():
     files_to_add = new_files + [fpath for fpath, _ in modified_files]
     if files_to_add:
         print(f"\nIndexing {len(files_to_add)} file(s)...")
-        docs = SimpleDirectoryReader(input_files=[str(f) for f in files_to_add]).load_data()
+        # Use "./" prefix to match paths from full build (pathlib strips it)
+        docs = SimpleDirectoryReader(
+            input_files=[f"./{f}" for f in files_to_add]
+        ).load_data()
         for doc in docs:
             index.insert(doc)