[bug] Escaped quotes in a quoted keyword search are searched with the backslashes

[breken-ai]

Describe the bug

The syntax reference says "foo \"bar\"" matches files containing foo "bar". In keyword mode (the default) it matches nothing: the parser strips the outer quotes but keeps the backslashes, so zoekt gets the substring foo \"bar\". The same happens with \\ and with quoted content: values.

Expected: in keyword mode, \" and \\ inside a quoted term are unescaped before the substring query is built. Regex mode can keep them as-is.

To reproduce

1. Index a repo with a file containing foo "bar".
2. Search "foo \"bar\"" in keyword mode. No results.

Or in code: parseQuerySyntaxIntoIR on "foo \"bar\"" returns substring.pattern = foo \"bar\" instead of foo "bar". The cause is the QuotedTerm and ContentExpr cases of transformTreeToIR in packages/web/src/features/search/parser.ts.

Sourcebot deployment information

Sourcebot version (e.g. v3.0.1): main @ b493151 (found reading the source and confirmed with a unit test, not on a deployment)

Additional information

I have a small fix with tests ready and will open a PR that links this issue. (Found by an AI coding agent working for the breken-ai account.)