feat(diagnostics): the admin log console

Admin → Diagnostics reads the server's stored log: one list, newest first,
where a line opens in place to its full record (time, source and logger,
account, request and job ids, version, message, attributes, stack). A
request or job id narrows the list to that request or job with every other
filter off, shown as a removable chip. Filters: level group, source,
account, event, period and a free-text search; all of them live in the URL
(`l*` keys, which setPage clears like the Plex and Channels keys), so a
filtered view is a link and Back restores it. "Live" re-reads the newest
page every few seconds while the tab is visible; paging into older rows
turns it off. Copy puts the loaded lines on the clipboard as JSON lines.

The facet counts now honour every filter but their own, as the feed's do:
a request pivot narrows them, and a picked level does not zero its
siblings. A value in use stays offered even when the counts drop it.

"Saját napló" and the console draw a line with one shared component,
`LogLine`, whose phone layout gives the message its own full-width line
(sharing the code's line left it a few characters). The level groups
moved to lib/log.ts for both.

The console's own reads are logged at DEBUG on success, like the
healthcheck: at INFO its live tail filled the log with itself.

backend/app/logs.py

@@ -638,9 +638,11 @@ def current_source() -> str:
 _REQUEST_ID_RE = re.compile(r"^[A-Za-z0-9._-]{8,64}$")
 
 # Paths whose success is logged at DEBUG rather than INFO: the container healthcheck runs every 15s
-# (5.7k lines/day saying nothing) and hashed static assets are served by the hundred per page load.
-# A FAILURE on either still logs at WARNING/ERROR — this lowers the floor, it does not hide.
-_QUIET_PREFIXES = ("/healthz", "/assets/", "/static/")
+# (5.7k lines/day saying nothing), hashed static assets are served by the hundred per page load, and
+# the admin log console reads the stored log — its live tail every few seconds, so at INFO the log
+# would fill with the console watching itself. A FAILURE on any of them still logs at WARNING/ERROR
+# — this lowers the floor, it does not hide.
+_QUIET_PREFIXES = ("/healthz", "/assets/", "/static/", "/api/admin/logs")
 
 # Not `siftlode.logs`: this is the replacement for uvicorn's ACCESS log, and `siftlode.http` is
 # what an operator pins a level on when they want request lines and nothing else. The module it