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/request/method.rs

@@ -49,6 +49,7 @@ pub enum MethodObject {
     DeletedAccount,
     // inbuxa: AI call limits
     AiLimits,
+    LogSettings,
     // inbuxa: "Explain this" with the local model
     Explanation,
     // inbuxa: the audit log
@@ -89,6 +90,7 @@ impl MethodObject {
             MethodObject::MaskedEmail => Capability::FastmailMaskedEmail,
             MethodObject::DeletedAccount => Capability::Inbuxa,
             MethodObject::AiLimits => Capability::Inbuxa,
+            MethodObject::LogSettings => Capability::Inbuxa,
             MethodObject::Explanation => Capability::Inbuxa,
             MethodObject::AuditEvent
             | MethodObject::AuditSettings
@@ -276,6 +278,8 @@ impl MethodName {
             (MethodFunction::Set, MethodObject::DeletedAccount) => "inbuxa:DeletedAccount/set",
             (MethodFunction::Get, MethodObject::AiLimits) => "inbuxa:AiLimits/get",
             (MethodFunction::Set, MethodObject::AiLimits) => "inbuxa:AiLimits/set",
+            (MethodFunction::Get, MethodObject::LogSettings) => "inbuxa:LogSettings/get",
+            (MethodFunction::Set, MethodObject::LogSettings) => "inbuxa:LogSettings/set",
             (MethodFunction::Set, MethodObject::Explanation) => "inbuxa:Explanation/set",
             (MethodFunction::Get, MethodObject::AuditEvent) => "inbuxa:AuditEvent/get",
             (MethodFunction::Query, MethodObject::AuditEvent) => "inbuxa:AuditEvent/query",
@@ -424,6 +428,8 @@ impl MethodName {
             "inbuxa:DeletedAccount/set" => (MethodObject::DeletedAccount, MethodFunction::Set),
             "inbuxa:AiLimits/get" => (MethodObject::AiLimits, MethodFunction::Get),
             "inbuxa:AiLimits/set" => (MethodObject::AiLimits, MethodFunction::Set),
+            "inbuxa:LogSettings/get" => (MethodObject::LogSettings, MethodFunction::Get),
+            "inbuxa:LogSettings/set" => (MethodObject::LogSettings, MethodFunction::Set),
             "inbuxa:Explanation/set" => (MethodObject::Explanation, MethodFunction::Set),
             "inbuxa:AuditEvent/get" => (MethodObject::AuditEvent, MethodFunction::Get),
             "inbuxa:AuditEvent/query" => (MethodObject::AuditEvent, MethodFunction::Query),
@@ -494,6 +500,7 @@ impl Display for MethodObject {
             MethodObject::MaskedEmail => "MaskedEmail",
             MethodObject::DeletedAccount => "inbuxa:DeletedAccount",
             MethodObject::AiLimits => "inbuxa:AiLimits",
+            MethodObject::LogSettings => "inbuxa:LogSettings",
             MethodObject::Explanation => "inbuxa:Explanation",
             MethodObject::AuditEvent => "inbuxa:AuditEvent",
             MethodObject::AuditSettings => "inbuxa:AuditSettings",