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>

config.py

@@ -0,0 +1,19 @@
+from dataclasses import dataclass, field
+import os
+
+
+@dataclass
+class APIConfig:
+    url: str = field(default_factory=lambda: os.getenv("YOULBOT_API_URL", "http://localhost:8000"))
+    token: str = field(default_factory=lambda: os.getenv("YOULBOT_API_TOKEN", ""))
+    timeout: int = 180
+
+
+@dataclass
+class AppConfig:
+    api: APIConfig = field(default_factory=APIConfig)
+    whisper_model_size: str = field(default_factory=lambda: os.getenv("WHISPER_MODEL_SIZE", "small"))
+    tts_voice: str = field(default_factory=lambda: os.getenv("TTS_VOICE", "Yuna"))
+    tts_edge_voice: str = field(default_factory=lambda: os.getenv("TTS_EDGE_VOICE", "ko-KR-SunHiNeural"))
+    server_host: str = "0.0.0.0"
+    server_port: int = 7860