[xPuffyPuffx]

Summary

This PR addresses two issues identified during conformance and sanitizer testing with AddressSanitizer and UndefinedBehaviorSanitizer:

1. Fractional seconds bounds check and validation in Timestamp::setTime (Time.cpp:82):
   When parsing fractional seconds (jsonDateString[19] == '.'), the validator checked:

   if (isdigit(jsonDateString[20]) ||
       isdigit(jsonDateString[21]) ||
       isdigit(jsonDateString[22]))

   Using logical OR (||) instead of logical AND (&&) caused two problems:

   • For truncated strings like "2024-01-01T12:00:00." (length 20) or "2024-01-01T12:00:00.1" (length 21), indices 21 and 22 read 1–2 bytes past the null terminator (global/stack buffer overread caught by ASan).
   • If non-digit characters were present (e.g. "2024-01-01T12:00:00.1abZ"), (c - '0') evaluated arbitrary ASCII characters as digits, generating corrupted millisecond values.
     Fix: Replaced || with &&. Because && short-circuits in C++ and isdigit('\0') is false, truncated strings stop immediately without reading past the buffer boundary.

2. Return NotImplemented for unregistered operations in TriggerMessage (TriggerMessage.cpp:70):
   OperationRegistry::deserializeOperation() returns a Request wrapping new NotImplemented() rather than nullptr when an operation is unregistered.
   Because if (msg) was always true, TriggerMessage erroneously set statusMessage = "Accepted" and queued the NotImplemented object into preBootSendQueue, which later caused Operation::createReq() to emit Unsupported operation: createReq() is not implemented and transmit a bogus empty CustomOperation Call frame.
   Fix: Checked if (msg && !msg->getOperation()->getErrorCode()) before accepting and queuing the operation.

Verification

Tested with host Clang, ASan, and UBSan against boundary timestamps ("2024-01-01T12:00:00.", "2024-01-01T12:00:00.1", "2024-01-01T12:00:00.123Z") and unregistered TriggerMessage requests. All unit tests pass with 0 sanitizer warnings.