Summary

• detect JSDoc-backed type assertions by scanning the trivia before the asserted expression instead of assuming as token ordering
• remove the JSDoc cast and trailing whitespace without touching the parenthesized expression, which avoids the inverted slice panic from issue panic in no-unnecessary-type-assertion autofix for JSDoc cast on parenthesized expression #780
• add a regression test that exercises a checked JavaScript file with /** @type {string} */ (s) and verifies the autofix output

Testing

• go test ./internal/rules/no_unnecessary_type_assertion/...
• reproduced the original crash with tsgolint headless --fix before the patch; verified it exits cleanly after the patch

Closes #780
Refs typescript-eslint/tsgolint#5