refactor: centralize llm provider transport

tools/build_architecture_inventory.py

@@ -127,7 +127,7 @@ def build() -> dict[str, Any]:
     tables = database_inventory(database_sources)
     return {
         "schema_version": 1,
-        "captured_from": "app modular preservation candidate",
+        "captured_from": "app accepted modular runtime",
         "runtime": {
             "http_server": "http.server.ThreadingHTTPServer",
             "application_processes": 1,
@@ -163,6 +163,10 @@ def build() -> dict[str, Any]:
             {"function": "compile_strategy_with_llm", "path": "backend/features/screener/compiler.py"},
             {"function": "test_llm_connection", "path": "backend/features/screener/compiler.py"},
         ],
+        "llm_transport": [
+            {"function": "chat_completion", "path": "backend/llm/transport.py"},
+            {"function": "stream_chat_completion", "path": "backend/llm/transport.py"},
+        ],
         "css_layers": css_layers(html),
         "code_hotspots": code_hotspots(),
     }