Enable typescript/no-unnecessary-type-assertion oxlint rule (#510)

* Initial plan

* Initial plan: Enable typescript/no-unnecessary-type-assertion rule

Co-authored-by: stipsan <81981+stipsan@users.noreply.github.com>

* Enable typescript/no-unnecessary-type-assertion oxlint rule

Co-authored-by: stipsan <81981+stipsan@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: stipsan <81981+stipsan@users.noreply.github.com>

Author: Copilot

.oxlintrc.json

@@ -19,6 +19,7 @@
   "rules": {
     "typescript/ban-ts-comment": "error",
     "typescript/no-deprecated": "error",
+    "typescript/no-unnecessary-type-assertion": "error",
     "typescript/prefer-ts-expect-error": "error",
     "import/no-commonjs ": "error",
     "import/no-unassigned-import": ["error", {"allow": ["**/*.css"]}],