feat: complete interactive wall of fame leaderboard (#5)

[arcursino]

📝 Description

This PR addresses issue #5 by implementing an interactive "Wall of Fame" developer leaderboard under the Leaderboard tab (tab_lead). It highlights community ecosystem contributions with an adaptive, production-safe UI while respecting background data limits.

🎯 Key Implementations

• Wall of Fame Grid: Generates responsive 4-column profile slots matching ScanAPI's aesthetic palette (#38bdf8) to prominently feature true author avatars and metrics.
• Dynamic Context-Aware Captions: Replaced static item trackers with an intelligent caption layer that automatically shifts context based on user-selected criteria (over the last 30 days vs. over a rolling 100-day window).
• Comprehensive Bot Filter: Built a reliable, case-insensitive string matcher that safely hides system-generated actions and dependencies (e.g., dependabot[bot]) when toggled.
• Data Normalization Safety: Optimized handling for date parsing, explicit timezones (.dt.tz_localize(None)), and missing/null fallback values to prevent calculation drops.

🛠️ Verification Steps

1. Navigate to the Leaderboard workspace tab.
2. Toggle the interactive options (e.g., switching from All Time to Last 30 Days).
3. Confirm that the subtle background helper caption updates its descriptive text dynamically to align with the active filtered timeframe.

🧪 Checklist

• Code formatted cleanly using the black src/ command lines.
• Code contains zero hardcoded database metric limits in UI typography.
• Commits follow standard open-source conventional guidelines.
• Successfully closes/links issue Gamification Leaderboards and Contributor Wall of Fame #5.