logging updates (SYN-8012)

[invisig0th]

Summary

Consolidate and modernize the Synapse logging infrastructure. Logging functionality previously scattered across synapse/common.py and synapse/lib/structlog.py is replaced by a dedicated synapse/lib/logging.py module with async-safe log pumping, structured output, and real-time log streaming APIs.

• New synapse/lib/logging.py module with JsonFormatter, TextFormatter, async StreamHandler, and log lifecycle management
• Async log pump task ensures logging never blocks the asyncio event loop
• Structured log output consistently formatted with system metadata that cannot be overwritten by user-provided information
• New logs() and watch() admin APIs on all Synapse services for retrieving recent log entries and streaming live log events
• Cell.getLogExtra() is now synchronous (no longer requires await)
• User context automatically included in log entries via s_scope
• Rich exception serialization including tracebacks, chained exceptions, and exception groups
• Removed synapse/lib/structlog.py and logging helpers from synapse/common.py
• Updated devops documentation with structured logging format details and examples
• Also includes $lib.lift.tagsByPref() Storm API (SYN-10503)

Key changes

Area	Description
synapse/lib/logging.py	New module (381 lines): setup(), shutdown(), reset(), logs(), watch(), getLogExtra(), setLogInfo(), excinfo(), formatters, async stream handler
synapse/lib/cell.py	getLogExtra() now sync, new logs()/watch() admin APIs, logging setup via s_logging.setup(), service name registered globally
synapse/lib/view.py	Storm execution logging uses s_scope.enter() for user context, getLogExtra() for structured params
synapse/common.py	Removed setlogging(), normLogLevel(), _getLogConfFromEnv() and related imports
synapse/lib/structlog.py	Deleted (replaced by synapse/lib/logging.py)
synapse/tests/utils.py	Refactored LoggerStream with async expect() method and queue-based log capture
docs/synapse/devopsguide.rst	Expanded structured logging documentation with field descriptions and JSON examples
60+ test files	Updated logging assertions to use new APIs and test utilities

Environment variables

SYN_LOG_LEVEL, SYN_LOG_STRUCT, and SYN_LOG_DATEFORMAT continue to work as before.