feat: 修复 H5 底部导航覆盖 + 更新项目进度文档

## H5 底部导航修复 (Bug #10)
- 精简 App.vue，移除重复 tabbar，仅保留全局样式
- uni-page 设置 height: calc(100% - 50px) + overflow-y: auto
- 内容区域精确停在底部导航上方，独立滚动不再叠加
- 恢复 custom-tab-bar 组件

## 项目进度文档
- PROGRESS.md 更新至 10 个 Bug 修复
- 新增 H5 底部导航修复记录
- 新增历史变更条目

backend/app/services/tts.py

@@ -0,0 +1,50 @@
+from typing import Optional
+import logging
+
+logger = logging.getLogger(__name__)
+
+try:
+    import edge_tts
+    HAS_EDGE_TTS = True
+except ImportError:
+    HAS_EDGE_TTS = False
+    logger.warning("edge-tts not installed, TTS disabled")
+
+VOICE_MAP = {
+    "zh": "zh-CN-XiaoxiaoNeural",
+    "en": "en-US-AriaNeural",
+    "ja": "ja-JP-NanamiNeural",
+    "ko": "ko-KR-SunHiNeural",
+    "fr": "fr-FR-DeniseNeural",
+    "de": "de-DE-KatjaNeural",
+    "es": "es-ES-ElviraNeural",
+    "pt": "pt-BR-FranciscaNeural",
+    "ru": "ru-RU-SvetlanaNeural",
+    "ar": "ar-SA-ZariyahNeural",
+}
+
+SUPPORTED_LANGS = list(VOICE_MAP.keys())
+
+
+class TextToSpeechService:
+    @staticmethod
+    async def synthesize(text: str, lang: str = "en", rate: str = "0%", pitch: str = "0Hz") -> Optional[bytes]:
+        if not HAS_EDGE_TTS:
+            logger.warning("edge-tts not available")
+            return None
+
+        voice = VOICE_MAP.get(lang, VOICE_MAP["en"])
+
+        try:
+            communicate = edge_tts.Communicate(text, voice, rate=rate, pitch=pitch)
+            audio_data = b""
+            async for chunk in communicate.stream():
+                if chunk["type"] == "audio":
+                    audio_data += chunk["data"]
+            return audio_data if audio_data else None
+        except Exception as e:
+            logger.error(f"TTS failed: {e}")
+            return None
+
+
+tts_service = TextToSpeechService()