Function init_tracing 

pub fn init_tracing(verbose: bool) -> Result<(), Box<dyn Error>>

Initialize tracing subscriber for structured logging (FR-OBS-001)

Sets up tracing with either compact (default) or verbose format. Verbose format includes spec_id, phase, duration_ms, and runner_mode fields.

Arguments

• verbose - If true, use verbose format with structured fields

Returns

Result indicating success or failure of initialization