Phase 26: P1 architecture refactor — DI container, service layer, async callbacks

- config.py: APIConfig + AppConfig dataclasses, env vars centralized
- api_client.py: APIClientProtocol (Protocol) + HTTPAPIClient class, remove module-level globals
- services.py: ChatService, DocumentService, TTSService (TTS moved from app.py)
- container.py: manual DI container with lazy singleton properties
- app.py: all callbacks converted to async, asyncio.run() fully removed, container wired in
- .env.example: add TTS_EDGE_VOICE entry
- ROADMAP.md: P0/P1 checklist updated to reflect completed work

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

container.py

@@ -0,0 +1,41 @@
+"""수동 DI 컨테이너."""
+from api_client import HTTPAPIClient
+from config import AppConfig
+from services import ChatService, DocumentService, TTSService
+
+
+class Container:
+    def __init__(self, config: AppConfig):
+        self._config = config
+        self._api_client: HTTPAPIClient | None = None
+        self._chat_service: ChatService | None = None
+        self._document_service: DocumentService | None = None
+        self._tts_service: TTSService | None = None
+
+    @property
+    def config(self) -> AppConfig:
+        return self._config
+
+    @property
+    def api_client(self) -> HTTPAPIClient:
+        if self._api_client is None:
+            self._api_client = HTTPAPIClient(self._config.api)
+        return self._api_client
+
+    @property
+    def chat_service(self) -> ChatService:
+        if self._chat_service is None:
+            self._chat_service = ChatService(self.api_client)
+        return self._chat_service
+
+    @property
+    def document_service(self) -> DocumentService:
+        if self._document_service is None:
+            self._document_service = DocumentService(self.api_client)
+        return self._document_service
+
+    @property
+    def tts_service(self) -> TTSService:
+        if self._tts_service is None:
+            self._tts_service = TTSService(self._config)
+        return self._tts_service