fix: S7780 — use String.raw for escaped strings (16 occurrences)

[RobertLD]

SonarCloud S7780 — Use String.raw to avoid escaping

16 occurrences where String.raw should be used instead of manual backslash escaping.

Affected files:

• src/core/ — packs.ts, parsers/csv.ts
• src/web/dashboard.ts
• Various test files (registry, reporter, parsers)

Fix: Replace string literals containing \\ escapes with String.raw\...`` where appropriate.

Severity: MINOR | Effort: ~20min