Add killerName to Mission model and enhance overlay components

- Introduced killerName field in the Mission model within the Prisma schema and created a corresponding migration.
- Updated mission management logic to assign a killerName during mission creation.
- Enhanced overlay components to display killer information, including avatar and name, in both expanded and minimized panels.
- Added new CSS styles for killer display in the overlay.
- Included new avatar images for various killers in the overlay assets.

CLAUDE.md

@@ -31,7 +31,7 @@ This is a Twitch Video Overlay extension implementing an autonomous tick-based Z
 - Sentence case in UI text and log messages.
 - Zod schemas (not just TS types) at the EBS boundary.
 - Pure functions for game logic. Seeded PRNG via `seedrandom`, never `Math.random()`. Persist seeds in `mission_logs`.
-- Migrations from day one. No "I'll add migrations later."
+- Migrations from day one. No "I'll add migrations later." After writing a migration file, always run `pnpm exec prisma migrate deploy --schema=apps/api/prisma/schema.prisma` immediately — the regenerated Prisma client will SELECT new columns on every query and cause 500s until the column exists in the database.
 - Round every displayed number; JS float math leaks artifacts.
 - Structured logging with correlation IDs (`missionId`, `tickIndex`, `channelId`, `opaqueUserId`).
 - Bind Nest services to `0.0.0.0`, not `127.0.0.1`. The Twitch dev rig on Windows reaches them via the WSL2/devcontainer port forwarding chain.