feat: "Advanced Tools" toggle in settings — progressive disclosure for power users

[ajithakdev]

Summary

Add an "Advanced Tools" master toggle in the settings page that unlocks technical features while keeping the default experience clean and simple.

The Philosophy

MeterX should be like a car:

• Default: Anyone can drive. Speedometer, fuel gauge, turn signals.
• Advanced: Pop the hood. Engine diagnostics, turbo modes, fine tuning.

Default Mode (for everyone)

• Speed test with quality badge (🟢 Excellent / 🟡 Fair / 🔴 Poor)
• App readiness labels (Calls ✅, Streaming ✅, Gaming ⚠️)
• ISP comparison ("72% of your plan")
• History & PDF export
• Simple, beautiful, zero jargon

Advanced Mode (toggle ON in settings)

Unlocks:

• 🔧 Raw metrics panel (jitter, packet loss, bufferbloat grade, DNS timing)
• 📊 Detailed charts with percentile distribution (p50, p90, p99)
• 🌐 Multi-server testing (test against different regions)
• 🛠️ DNS benchmark tool
• 🔍 Network path tracer (hop analysis)
• 📈 Bufferbloat deep-dive (loaded vs unloaded latency graph)
• 🔔 Custom notification thresholds (by exact Mbps/ms values)
• 💾 Custom export formats (JSON, CSV, Markdown)
• ⚙️ Test configuration (stream count, duration, chunk size)
• 📶 Wi-Fi Sweet Spot Finder
• 🛡️ Throttling detector
• 🧪 Connection stress test mode

Implementation

• Single toggle: chrome.storage.sync key advancedMode: boolean
• UI conditionally shows/hides advanced sections with smooth CSS transitions
• All features still available in code — just hidden from UI when toggle is off
• Toggle location: Settings page, near the top, with explanation text
• Popup and side panel read this preference and adapt their layout

Why

• Non-technical users see a clean, approachable tool (they're 95% of users)
• Technical users get all the power tools they want (and they're the ones who recommend tools to friends)
• Both audiences feel MeterX was "made for them"
• This is how iPhone (simple) vs Android (customizable) both succeed