Downweight browser rescue catch blocks

[aouxwoux]

Summary

• tune try/catch scoring so browser-boundary rescue blocks receive a stronger downweight than other boundary code
• keep browser catch findings visible instead of exempting them entirely
• add a heuristic regression covering browser API fallback catches versus core logic catches

Fixes #3

Tests

• �un test tests/heuristics.test.ts
• �un run lint
• oxfmt --check src/rules/shared/try-catch-rule-helpers.ts tests/heuristics.test.ts

Notes

• �un test has existing Windows CLI spawn failures where output.status is undefined in CLI fixture tests.
• The repo-wide pre-commit oxfmt --check . fails on this Windows checkout across many untouched files; the touched files pass the formatter check above.