Add oxlint for type-aware linting that Biome cannot cover

Install oxlint with tsgolint for TypeScript type information. Enable
rules for unnecessary type assertions, deprecated API usage, preferring
replaceAll over replace with global regex, and String.raw for escaped
backslashes. Fix all violations: remove redundant as-casts, replace
deprecated FormEvent with SubmitEvent, convert replace(/g) to
replaceAll, and use String.raw in escapeRegExp. Add oxlint to the
pnpm check gate alongside Biome.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/src/hooks/use-encounter.ts

@@ -303,8 +303,8 @@ export function useEncounter() {
 			// Derive creatureId from source + name
 			const slug = entry.name
 				.toLowerCase()
-				.replace(/[^a-z0-9]+/g, "-")
-				.replace(/(^-|-$)/g, "");
+				.replaceAll(/[^a-z0-9]+/g, "-")
+				.replaceAll(/(^-|-$)/g, "");
 			const cId = makeCreatureId(`${entry.source.toLowerCase()}:${slug}`);
 
 			// Set creatureId on the combatant (use store.save to keep ref in sync for batch calls)