Add configurable log file mode with date-first naming convention

[JayVDZ]

Features:

• Add LogFileMode configuration option (Daily or PerExecution)
• Daily mode: Creates YYYYMMDD-scheduler.log (one file per day, shared by all executions)
• PerExecution mode: Creates YYYYMMDDHHmmss-scheduler.log (unique file per execution)
• Date-first naming convention for better sorting and organization
• Backward compatible - defaults to Daily mode if not specified

Implementation:

• Add LogFileMode setting to App.config
• Update InitialiseLogging() to support both modes
• Daily mode creates single log file per day (e.g., 20251124-scheduler.log)
• PerExecution mode creates unique log per execution (e.g., 20251124143052-scheduler.log)

Tests:

• Add 8 comprehensive integration tests for logging configuration
• Test file naming patterns, uniqueness, and mode defaulting behavior
• Verify Daily mode uses same file for multiple executions on same day
• Verify PerExecution mode creates unique files per execution
• All 45 tests passing (37 original + 8 new)

Documentation:

• Update README.md with LogFileMode configuration details
• Update DEVELOPMENT.md with feature branch SOP and log file format details
• Add examples and use case guidance for each mode

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