Adds a preset-based settings system to the mobile dashboard and fixes LED behavior to properly account for WiFi operating modes.

[jctoledo]

Dashboard UI - Driving Presets

New preset selector replaces the always-visible 8-slider interface:

• Track - High thresholds (0.30g accel, 0.50g brake/lateral) for racing/autocross
• Canyon - Medium-high (0.20g/0.35g/0.30g) for spirited twisty road driving
• City - Default values (0.10g/0.18g/0.12g) for daily driving
• Highway - Lower thresholds (0.08g/0.15g/0.10g) with higher min speed for cruise
• Custom - Full slider access for fine-tuning

UX improvements:

• One-tap preset selection instantly applies settings to ESP32
• Compact summary view shows current values when not in Custom mode
• Sliders only visible in Custom mode (reduces UI clutter)
• Expanded slider ranges for track use (up to 0.80g accel/brake, 1.0g lateral)
• Settings auto-detected on page load and matched to nearest preset

LED Behavior Fixes

Mode-aware status indication:

• MQTT disconnection LED (2 red blinks) now only shows in Station mode
• In Access Point mode, MQTT is not used so no misleading red blinks occur

New settings confirmation pattern:

• 3 green-white alternating flashes when settings are changed via dashboard
• Provides visual feedback that preset/custom settings were applied