Strict time validation + antagonist suite + compute refactor

[matiasandina]

Summary

• Adds strict time validation for samples/intervals/alignment to prevent silent bad output.
• Introduces antagonist test suite + fixtures and a triage doc/roadmap updates.
• Refactors compute helpers and refreshes docs/tests/demo data.

Key changes

• Strict time checks: x/xend must be complete and time-like; non-monotonic x now errors; explicit interval must be finite and > 0.
• Intervals now error on xend < x and warn on xend == x.
• Alignment now errors if x/xend contain missing/non-finite values.
• New antagonist cases and combined entrypoint script.
• Updated demos, snapshots, and compute tests.

Breaking-ish behavior

• Previously tolerated inputs (NA x/xend, non-monotonic x, invalid interval) now error.

Testing

• Rscript tests/antagonist/ggethos_attack_all.R

[matiasandina]

These are degenerating into barplots ?

[matiasandina]

Major refactor passing checks. We'll continue testing and using improvement roadmap