fix(codegen): replace unsafe unwraps with error context and robust ma…

[goodbsw]

Description

This PR addresses latent panic risks within the k8s-pb-codegen binary by refactoring aggressive .unwrap() calls into idiomatic Rust error-handling patterns using anyhow::Context.

As an infrastructure engineering component, the code generator should gracefully bubble up errors rather than inducing unexpected panics during build time, especially within multi-cluster CI/CD pipelines.

Key Changes

• Eliminated unwrap() in Module Tree Traversal: Refactored the while !parts.is_empty() loop to use an atomic while let Some(module) = parts.pop() pattern, preventing potential index or bounds panics structurally.
• Robust Path & Directory Handling: Added explicit .with_context() tracking to all dst.parent() resolutions and std::fs::create_dir_all calls to provide granular diagnosis if I/O blockages occur.
• Safer Trait Generation Pipeline: Updated signature of append_trait_def and append_trait_impl to return anyhow::Result<()>. Replaced writeln!(...).unwrap() with ? propagation to catch disk capacity or broken pipe anomalies gracefully.
• Cleaned Up prost_build Propagation: Aligned the Protobuf compilation phase with consistent anyhow context mapping.

Diagnostics Verified

Successfully validated workspace compilation against all targets:

cargo check --workspace --all-targets
# Output: Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.39s