Fix stale Search CLI guidance

[georgeatparallel]

Our CLI help still carries old Beta-era guidance: an expired June 2026 deadline for Search mode aliases, an unclear date boundary, and a 1,000-character excerpt minimum. We update the guidance so users can choose options without working around limits that no longer apply.

We keep the old mode names working for existing scripts: fast and one-shot still map to basic, and agentic still maps to advanced. Help now lists turbo, basic, and advanced first, and the deprecation warning names the replacement mode without an expiry date. We also describe --after-date as inclusive and remove the obsolete excerpt minimum from both Search and Extract help. These are guidance changes; they do not change date filtering or excerpt handling.

Our tests cover the help text and full warning message, check that all three native modes avoid warnings, and retain checks for alias translation and clean JSON output.

Validation

Recorded validation: 781 tests passed; ruff check --fix ., ruff format ., tach check, ty check, and git diff --check completed. The rendered parallel-cli search --help output was also checked.