🧹 Refactor executePptxOp into domain-specific handlers

[MarsLuay]

🎯 What

Refactored executePptxOp in src/ai/pptxOpExecutor.ts by splitting its monolithic 32-case switch statement into domain-specific helper functions (executeTextOp, executeShapeOp, executeInsertionOp, executeSlideOp, executeMediaOp, executeChartOp).

💡 Why

executePptxOp was over 400 lines long, making it hard to read and maintain. Extracting modular domain handlers improves readability and maintainability while preserving exact operational behavior.

✅ Verification

• npm run typecheck passed cleanly.
• node --test tests/ai-op-smoke.test.mjs passed all 45 test assertions.
• Code review confirmed logic preservation with zero regressions.

✨ Result

Code health is improved with a modular structure that makes individual PowerPoint operations easier to navigate and maintain.

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PR created automatically by Jules for task 7252858160250275925 started by @MarsLuay

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