Keep rotated log files for a set number of days

Personal-data catalog spec, default D1 (settled 2026-09-28): log files
were never deleted. inbuxa:LogSettings.keepForDays says how many days
rotated log files are kept; unset (null) keeps every file, as before,
and a new install sets 30 days.

It is a fork-owned setting, stored under T + l as audit retention is,
not a field on x:TracerLog: that object is also stored inside
x:Bootstrap with a field after it, so a new field would change
x:Bootstrap's stored format. Server-level, with the tracers'
permissions (sysTracerGet, sysTracerUpdate); changes are in the audit
log, before and after.

Log files are local, so every node deletes its own: hourly, and at once
when the setting changes on that node. Only regular files named
<prefix>.<something> in each enabled log tracer's directory, last
changed more than the limit ago, are removed; the file being written is
never that old, and nothing else in the directory is touched. Minimum
one day. The catalog classifies inbuxa:LogSettings and points the log
file's retention at it.

Tested: unit tests for the file rule (only this log's old files; the
current file, other files and directories stay) and a purge on disk;
the system suite, which reads, sets, refuses zero, restores null and
checks the audit records; fork checks.

crates/jmap-proto/src/response/mod.rs

@@ -103,6 +103,7 @@ pub enum GetResponseMethod {
     MaskedEmail(GetResponse<crate::object::fastmail_masked_email::FastmailMaskedEmail>),
     DeletedAccount(GetResponse<crate::object::inbuxa_deleted_account::DeletedAccount>),
     AiLimits(GetResponse<crate::object::inbuxa_ai_limits::AiLimits>),
+    LogSettings(GetResponse<crate::object::inbuxa_log_settings::LogSettings>),
     AuditEvent(GetResponse<crate::object::inbuxa_audit::AuditEvent>),
     AuditSettings(GetResponse<crate::object::inbuxa_audit::AuditSettings>),
     AccountLock(GetResponse<crate::object::inbuxa_account_lock::AccountLock>),
@@ -136,6 +137,7 @@ pub enum SetResponseMethod {
     MaskedEmail(Box<SetResponse<crate::object::fastmail_masked_email::FastmailMaskedEmail>>),
     DeletedAccount(Box<SetResponse<crate::object::inbuxa_deleted_account::DeletedAccount>>),
     AiLimits(Box<SetResponse<crate::object::inbuxa_ai_limits::AiLimits>>),
+    LogSettings(Box<SetResponse<crate::object::inbuxa_log_settings::LogSettings>>),
     AuditSettings(Box<SetResponse<crate::object::inbuxa_audit::AuditSettings>>),
     AuditExport(Box<SetResponse<crate::object::inbuxa_audit::AuditExport>>),
     AuditVerification(Box<SetResponse<crate::object::inbuxa_audit::AuditVerification>>),
@@ -349,12 +351,24 @@ impl<'x> From<GetResponse<crate::object::inbuxa_ai_limits::AiLimits>> for Respon
     }
 }
 
+impl<'x> From<GetResponse<crate::object::inbuxa_log_settings::LogSettings>> for ResponseMethod<'x> {
+    fn from(value: GetResponse<crate::object::inbuxa_log_settings::LogSettings>) -> Self {
+        ResponseMethod::Get(GetResponseMethod::LogSettings(value))
+    }
+}
+
 impl<'x> From<SetResponse<crate::object::inbuxa_ai_limits::AiLimits>> for ResponseMethod<'x> {
     fn from(value: SetResponse<crate::object::inbuxa_ai_limits::AiLimits>) -> Self {
         ResponseMethod::Set(SetResponseMethod::AiLimits(Box::new(value)))
     }
 }
 
+impl<'x> From<SetResponse<crate::object::inbuxa_log_settings::LogSettings>> for ResponseMethod<'x> {
+    fn from(value: SetResponse<crate::object::inbuxa_log_settings::LogSettings>) -> Self {
+        ResponseMethod::Set(SetResponseMethod::LogSettings(Box::new(value)))
+    }
+}
+
 impl<'x> From<SetResponse<crate::object::inbuxa_explanation::Explanation>> for ResponseMethod<'x> {
     fn from(value: SetResponse<crate::object::inbuxa_explanation::Explanation>) -> Self {
         ResponseMethod::Set(SetResponseMethod::Explanation(Box::new(value)))