Feature: Add decision limit selector (5/10/20/50 options)

[xqliu]

Feature Request

Description

Add a dropdown selector to allow users to choose how many decision records to display in the Web UI.

Problem Statement

Currently, the system only displays the most recent 5 decision records (approximately 15 minutes of history). Users cannot review longer periods of AI decision history through the Web UI, which is especially problematic when:

• Remote server access is not available
• Accessing from mobile devices or tablets
• Users need to analyze AI trading patterns over longer periods

Proposed Solution

Add a dropdown selector with options: 5 / 10 / 20 / 50 records.

Time Coverage

Records	Time Coverage	Use Case
5	15 minutes	Quick status check (default)
10	30 minutes	Short-term review
20	1 hour	Medium-term analysis
50	2.5 hours	Deep pattern analysis

Implementation Details

Backend Changes

• Add limit query parameter to /api/decisions/latest endpoint
• Default: 5 (maintains current behavior)
• Max: 50 (prevents excessive data loading)
• Fully backward compatible

Frontend Changes

• Add dropdown selector UI component
• Persist user selection in localStorage
• Update API calls with selected limit

User Benefits

1. Better monitoring: Review AI decisions over longer periods
2. Pattern analysis: Identify trends in AI trading behavior
3. Mobile-friendly: No need for SSH access to server logs
4. Flexible: Users can choose their preferred view

Backward Compatibility

✅ Fully backward compatible - API defaults to 5 when parameter is not provided

Performance Impact

• Minimal: ~50-100KB additional data for 50 records
• No noticeable impact on loading time

Priority

Medium - Enhances user experience without affecting core functionality

Related PR

Will be linked once PR is created