feat(dx): add plan-log workflows

[gbin]

Summary

• Extend the shared plan recipe to generate logstats and feed them into cu29-plan.
• Add just plan-log with automatic local Copper log and typed logreader discovery.
• Add the same workflow to generated single-crate and full-workspace templates.
• Cover generated Justfiles and document the new command.

Stack

PR 4 of 4.

• Depends on feat(plan): render observed execution timing #1251.
• feat(plan): render observed execution timing #1251 depends on feat(logstats): export observed schedule timing #1250.
• feat(logstats): export observed schedule timing #1250 depends on fix(logstats): resolve config features and mission defaults #1249.

Review and merge from the bottom of the stack upward.

Verification

• Final stacked tree is byte-for-byte equivalent to the original feat(dx): add plan-log workflows #1245 tree.
• Rust formatting, Python syntax, Justfile parsing, and diff whitespace checks passed.
• Full workspace verification is deferred to CI because the local checkout is missing the optional sibling cu-vitfly path dependency.