* perf: filter tool diagnostics to only edited files
Tools (edit, write, apply_patch) stored LSP diagnostics for ALL project
files in their metadata. In large projects this adds 100-500KB of
unrelated diagnostics per tool call, bloating session payloads by
50-77%.
The UI only renders diagnostics for the edited file(s), so the rest is
dead weight. Extract a filterDiagnostics utility that keeps only the
relevant files' diagnostics and use it in all three tools.
* add kilocode_change marker to diagnostics filter test
Marius
8551d95447