Phase 2: scoring engine with full branch coverage

Pure functions in src/lib/scoring implementing docs/SCORING.md: cell values
(override > judge average), weighted raw totals, raw and placement points
with tie averaging, and competition-ranked standings. Coverage thresholds
are enforced at 100% for the module. Also silences the hydration warning
caused by browser extensions modifying <html>.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -10,7 +10,8 @@
     "test": "vitest run",
     "test:watch": "vitest",
     "check:rls": "node --env-file=.env.local scripts/check-rls.mjs",
-    "gen:types": "node --env-file=.env.local scripts/gen-types.mjs"
+    "gen:types": "node --env-file=.env.local scripts/gen-types.mjs",
+    "test:coverage": "vitest run --coverage"
   },
   "dependencies": {
     "@supabase/ssr": "^0.12.7",