Fix stale Search CLI guidance

[georgeatparallel]

Summary

• List V1-native Search modes first while preserving the Beta mode aliases for compatibility.
• Replace the expired June 2026 alias warning with durable deprecation guidance.
• Describe after_date as inclusive and remove the obsolete 1,000-character excerpt minimum from Search help.
• Strengthen help and deprecation tests so stale lifecycle claims cannot pass through substring-only assertions.

Why

The CLI had inherited Search help text from older Beta-era constraints. The aliases still work and map to V1 modes, after_date includes the specified date, and the API no longer imposes a 1,000-character minimum for Search excerpts.

Validation

• 781 tests passed.
• ruff check --fix .
• ruff format .
• tach check
• ty check
• Verified the rendered parallel-cli search --help output.
• git diff --check