perf: pre-compress gamedata JSON, tune MariaDB, fix avatar imager, docs

- scripts/compress-gamedata.mjs: pre-compress large gamedata JSON to .gz
  (gzip level 9, idempotent mtime check) served via nginx gzip_static
  (48 MB FurnitureData.json -> ~2.4 MB, ~0.3s -> ~0.005s per request)
- package.json: add gamedata:compress script
- fix(imaging): accept real Habbo figure strings in avatar route
  (allow optional second number per part, e.g. hd-180-1.ch-210-66)
- README: document avatar imager container (avatar-imaging-pixinode,
  port 8082, /docker/Polaris-imager), nginx /imaging proxying, MariaDB
  tuning, gamedata pre-compression cron and caching layers

package.json

@@ -24,6 +24,7 @@
 		"db:migrate": "tsx scripts/apply-migrations.ts",
 		"db:migrate:status": "tsx scripts/apply-migrations.ts --status",
 		"db:studio": "drizzle-kit studio",
+		"gamedata:compress": "node scripts/compress-gamedata.mjs",
 		"hk:matrix:check": "tsx scripts/verify-housekeeping-matrix.ts",
 		"test:housekeeping": "vitest run --coverage.enabled=false src/features/housekeeping src/lib/admin-theme-source-audit.test.ts src/lib/admin/authorization-contract.test.ts",
 		"prepare": "node scripts/prepare-hooks.mjs",