The error_log table had no retention policy: every backend error was
appended forever, so across months of dogfooding it grew unbounded. That
silently bloats the diagnostic-bundle export and slows the
list_recent_errors query the Settings → About panel runs.
- New `kon_storage::prune_error_log(pool, keep_days)` does a single
`DELETE FROM error_log WHERE timestamp < datetime('now', '-Nd days')`
and returns the row count removed.
- src-tauri/src/lib.rs runs it once during setup() with a const
ERROR_LOG_RETENTION_DAYS = 90. Failure is logged to stderr but does not
block startup — a prune that fails is strictly less important than the
app coming up.
- Test: insert three rows at now / -30d / -200d, verify a 90-day prune
removes only the oldest, and a subsequent 14-day prune removes the
-30d row. Storage suite at 60/60.
https://claude.ai/code/session_0189xUb6ie6t9qHkzatGZ9Rb
c04c719d48