Review fixes for the Diagnostics & logs section:
- Clear all logs reads the log files again before it confirms, so the
dialog names the copies it deletes now (a list it cannot read gives the
general sentence, never an old count); Refresh reads the files too.
- Runtime values that cannot be read stay disabled and say so.
- Create test link holds its button until the write answered, so a second
press cannot write a second record.
- The Lines field names its range.
- The browser server builds its logger in its own root, so no log file is
ever opened in another folder; the fixture closes every directory scan
and replaces a link instead of writing through it.
- system.mjs drops the unused section fallback; frontend coverage floors
recorded with coverage:update (system-diagnostics.mjs 97.5% lines).
Part of #329
Vito Sansevero
91cdb23029