Create developer activity insights in `insights/developer-activity`

[ccerv1]

Vision: Replicate standard Electric Capital charts

Required Charts:

1. High-Level Metrics Panel:
   • Full-time developers
   • Monthly active developers
   • Total repos
   • Total commits
   • Should be selectable by ecosystem
2. Main Activity Chart:
   • Show full-time devs, monthly active devs, new developers over time
   • Selectable by ecosystem
   • Similar to Electric Capital's main visualization
3. Activity Breakdown Chart:
   • Breakdown by developer type (full-time, part-time, etc.)
   • Show contributions by category
4. Active Developers by Tenure:
   • Chart showing distribution of active developers by how long they've been contributing
   • Standard Electric Capital visualization
5. Deep Dive/Leaderboard (Enhancement Request):
   • Beyond the ecosystem-level view, show individual contributors
   • Table/leaderboard showing:
     • Biggest contributing organizations
     • Biggest contributing developers
   • Allow drilling down into specific ecosystems to see who's leading

Example Reference: Should match Electric Capital's Solana/Ethereum dashboard style

https://www.developerreport.com/ecosystems/ethereum-virtual-machine

[linear]

OSO-1430