Partition report files by launcher and expand report templates

Normalized profile

What this task asks for

Split report output into per-launcher files with template expansion, launcher-safe filenames, and per-launcher summaries. Report_file must support <launcher>, <date>, <timestamp> template variables. When <launcher> is present, Reporter must create separate files and route each browser's results to its own file. Finish() must be idempotent. Launcher names in filenames must be filesystem-safe (each /\:*?"<>|() becomes one underscore, and consecutive whitespace becomes one underscore). The internal "testem" launcher must not produce a file. TAP reporter must optionally show per-launcher pass/fail/skip counts.