Add a report governor in app.main.errors: each report carries
a fingerprint, the first occurrence is always emitted, and
repeats within 2 minutes are counted and included in the next
emitted report as :occurrences. The fingerprint cache is
bounded by evicting the oldest entry.
flash reserves the report before generating it, so suppressed
occurrences do not build a report. static.cljs now passes the
cause so the exception page gets a full fingerprint.
Closes#11726
AI-assisted-by: deepseek-v4.1-flash
ee651b86d8