✨ Add oxlint-tsgolint for type-aware linting

Activates type-aware rules via oxlint --type-aware, backed by
oxlint-tsgolint (TypeScript-Go). Catches unsafe type assertions,
unnecessary type parameters, and other issues regular oxlint
cannot see.

- Add oxlint-tsgolint devDep + 6 platform-specific native bindings
  as optionalDependencies (same pattern as oxlint)
- Add --type-aware flag to check:oxlint
- Add 6 @oxlint-tsgolint/* platforms to check:outdated ignore list
- Disable 3 type-aware rules in .oxlintrc.json with rationale:
  - typescript/no-unsafe-type-assertion, typescript/no-unnecessary-type-parameters:
    fire on legitimate generic type machinery in keysMatch/MatchBuilder
    that needs type-system restructuring (deferred to a follow-up)
  - typescript/no-floating-promises in test files: expectTypeOf() is
    a sync type-assertion library that oxlint-tsgolint misidentifies

Code simplifications enabled by the new strict checks:
- src/match.ts: drop value as unknown casts (T is already assignable
  to unknown) and the redundant run(value) as R cast
- src/index.test.ts: drop unnecessary 'X' as 'X | Y' assertions in
  match<...>(...) calls (literals are already assignable to the union)

Documentation updates in project-specs.md and README.md. Add
'tsgolint' to cspell word list.

src/match.ts

@@ -14,7 +14,7 @@ interface MatchBuilder<T, R> {
 const buildMatch = <T, R>(value: T, cases: Cases<R>): MatchBuilder<T, R> => {
     const apply = (): R | undefined => {
         for (const [matcher, handler] of cases) {
-            if (matcher.matches(value as unknown)) {
+            if (matcher.matches(value)) {
                 return handler(value);
             }
         }
@@ -43,8 +43,8 @@ const buildMatch = <T, R>(value: T, cases: Cases<R>): MatchBuilder<T, R> => {
         },
         otherwise(handler: (value: T) => R): R {
             for (const [matcher, run] of cases) {
-                if (matcher.matches(value as unknown)) {
-                    return run(value) as R;
+                if (matcher.matches(value)) {
+                    return run(value);
                 }
             }
             return handler(value);