#2830 Telemetry: mark paths where errors are built so redaction needs no guessing

Follow-up to swamp-club#2817 (PR swamp-club/swamp#2744).

Error-message redaction now removes known values exactly (what the user typed, plus the working, home and repo directories) and falls back to path patterns. One gap remains: a path whose last segment contains a space, which neither came from the command line nor sits under a known directory (for example a discovered file), still sends its last word, because no pattern can tell where such a path ends.

Proposal: errors that include a path pass it as a separately marked value (for example a UserError paths field, or a small helper that wraps the path), and telemetry replaces exactly those values with PATH. The free-text patterns stay only as the fallback for third-party error strings. Serve-executed runs, which have no command line and so no known values, benefit most.