Add CLI flag to enable internal bundler tracing for diagnostics

Add CLI flag to enable internal bundler tracing for diagnostics targets a $1.2B = 300K web engineering teams × $4K ACV total addressable market with medium saturation and a year-over-year growth rate of 15% YoY — estimated growth for developer tooling and observability driven by increased web app complexity and CI usage (based on industry reports like State of JS, StackOverflow trends, and vendor growth signals).

Key trends driving demand: Front-end build complexity is increasing as frameworks and bundlers add optimizations — this creates demand for better build-time observability to maintain fast feedback loops.; Shift-left observability practices encourage capturing traces locally and in CI, creating opportunities for developer-first trace tooling that works before production.; Open-source-first developer tooling adoption remains strong, and companies prefer a low-friction OSS onramp before paying for advanced SaaS features..