Feat/qq local file upload

[alexhoshina]

📝 Description

🗣️ Type of Change

• 🐞 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 📖 Documentation update
• ⚡ Code refactoring (no functional changes, no api changes)

🤖 AI Code Generation

• 🤖 Fully AI-generated (100% AI, 0% Human)
• 🛠️ Mostly AI-generated (AI draft, Human verified/modified)
• 👨‍💻 Mostly Human-written (Human lead, AI assisted or none)

🔗 Related Issue

📚 Technical Context (Skip for Docs)

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• Reasoning:

🧪 Test Environment

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📸 Evidence (Optional)

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☑️ Checklist

• My code/docs follow the style of this project.
• I have performed a self-review of my own changes.
• I have updated the documentation accordingly.

[yinwm]

Code Review Approved ✅

Assessment

• Code Quality: High
• Test Coverage: Comprehensive (444 lines of new tests)
• Error Handling: Robust
• Documentation: Updated

Highlights

1. Well-designed two-step upload flow (upload then send)
2. max_base64_file_size_mib config to limit memory usage
3. Bonus features: inbound attachment support and botgo log filtering
4. Tests cover all critical paths

⚠️ Note

Found two other overlapping PRs:

• #1726 (xiang33)
• #1227 (zboya)

Recommend merging this PR first, then closing the others or incorporating their improvements (file caching, retry mechanism) in a follow-up.