feat: 新增智慧簡報旁白生成系統 (Smart Slide Voiceover System)

- 新增 Excel 輸入模組：解析 .xlsx 格式講稿檔案
- 新增 TTS 引擎模組：整合 edge-tts 調用 Azure Neural Voice
- 新增 PyQt6 圖形介面：檔案選擇、語音選擇、進度監控
- 新增執行緒模型：QThread + Asyncio 確保 UI 響應性
- 支援 10 種 Neural Voice (中文/越南/英文)
- 支援中英混雜、越英混雜發音

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

AGENTS.md

@@ -0,0 +1,18 @@
+<!-- OPENSPEC:START -->
+# OpenSpec Instructions
+
+These instructions are for AI assistants working in this project.
+
+Always open `@/openspec/AGENTS.md` when the request:
+- Mentions planning or proposals (words like proposal, spec, change, plan)
+- Introduces new capabilities, breaking changes, architecture shifts, or big performance/security work
+- Sounds ambiguous and you need the authoritative spec before coding
+
+Use `@/openspec/AGENTS.md` to learn:
+- How to create and apply change proposals
+- Spec format and conventions
+- Project structure and guidelines
+
+Keep this managed block so 'openspec update' can refresh the instructions.
+
+<!-- OPENSPEC:END -->