feat: tell the collector how far to trust the timestamp - #57

Add SolidSyslogTimeQualitySd, and give MetaSd an uptime source alongside its counter.

struct SolidSyslogMetaSdConfig metaConfig = {
 .Counter = SolidSyslogStdAtomicCounter_Create(),
 .GetSysUpTime = SolidSyslogFreeRtos_GetSysUpTime, /* new */
};
sd[1] = SolidSyslogTimeQualitySd_Create(SyslogTimeQuality);

... BOOT [meta sequenceId="1" sysUpTime="385"][timeQuality tzKnown="1" isSynced="0"] device started

Time quality states how far the clock can be trusted, which matters when comparing events from
different devices.

This device reads the host clock once at boot and then free-runs on the FreeRTOS tick, so isSynced
is 0 and the callback writes no syncAccuracy. tzKnown is 1; the device works in UTC
throughout.

sysUpTime accompanies the sequence number. After a reboot the sequence restarts at one, and an
uptime near zero distinguishes that from a counter wrap. It is one more field on a config struct
that already existed.

The element lands before the store because store-and-forward breaks the assumption that a record
reaches the collector shortly after it was raised. A record can arrive hours later, so the device
states what its clock is worth first.

Summary by CodeRabbit

• New Features

  • Syslog records now include system uptime metadata.
  • Added time-quality metadata indicating timezone availability and whether the clock is synchronized.
  • Improved support for interpreting delayed records and detecting reboots through uptime information.

• Documentation

  • Updated configuration guidance, resource usage details, and example output for the new time-quality metadata.
  • Refreshed validation reports and measurement references.