feat(linbo-remote): prune old per-run logs, rotate the run record

[HappyBasher]

Part 3 of #179. Stacked on #184 (which is stacked on #183); retarget to main once those are merged.

• pruneRunLogs() deletes per-run logs (<host>_linbo-remote_<timestamp>.log) older than 90 days (RUN_LOG_RETENTION_DAYS) when a new run starts. Best effort, only touches files matching the per-run name.
• logrotate can't do this: per-run logs have unique names, so it would never delete the small ones, and its size 50k rule would rotate a large one into an empty file of the same name. The existing stanza therefore becomes *[!0-9].log, which leaves them out (all other logs are still matched, checked with logrotate -d on a live server).
• New stanza rotates linbo-remote_runs.jsonl monthly, 12 kept, compressed.
• Verified on a live server: a 200 day old per-run log was removed by the next run, an equally old rsync-*.log stayed.

Refs #179

🤖 Generated with Claude Code

[TomlDev]

Thanks for this. A review of the code, with the points a consumer (linuxmuster-api, webui7, edulution) runs into:

Line references are to the files on the PR branches (linbo_remote_lib.py = src/serverfs/usr/share/linuxmuster/linbo/linbo_remote_lib.py).

1. *[!0-9].log in logrotate.d/linuxmuster-linbo7:4 also stops rotating every other log whose name has a digit before .log, not just the per-run ones. Today none of the shipped names qualify, but a future foo2.log silently never rotates (no error, the file grows).
Suggestion: put the per-run logs in a subdirectory ($LINBOLOGDIR/linbo-remote/), which keeps the old *.log stanza unchanged and lets pruneRunLogs match on the directory instead of a regex; or keep the glob and add a spec that fails when a new *.log writer in the repo ends in a digit.

2. Record retention (12 months) is longer than log retention (90 days) (RUN_LOG_RETENTION_DAYS, rotate 12 in the jsonl stanza), so most log entries in linbo-remote_runs.jsonl.*.gz point to files that no longer exist. Either state it in the README (consumers must treat a missing log as normal) or align the two (rotate 3).

3. Legacy <host>.linbo-remote files are never cleaned up (no logrotate match, not covered by _RUN_LOG_RE). Add a one-time removal in the package postinst, or leave them and document it; with #183 point 1 they would otherwise stay readable but stale.

4. Rotated naming for consumers. Without dateext/delaycompress the rotated files are linbo-remote_runs.jsonl.1.gz ... .12.gz and renumber every month. Add this to the README ("read linbo-remote_runs.jsonl plus .N.gz in ascending N; do not cache by file name").

Checked and fine (no action): per-line appends are serialized by flock and >> (30 parallel runs gave 30 intact lines), ensure_ascii JSON plus shlex.quote keeps quotes, backslashes, newlines and unicode intact in the record, no copytruncate needed because the file is reopened per write, create 644 root root is readable by linuxmuster-api (service has no User=, runs as root), _RUN_LOG_RE does not match .1.gz, _linbo.log, rsync-*.log or the jsonl.