docs: gate growth actions on complete evidence

[moose-lab]

Summary

• Adds an explicit evidence gate to AGENTS.md so incomplete strategy reports, SEO/GEO supervisor reports, generated experiment reports, audit workbooks, and Obsidian summaries cannot drive the next growth decision.
• Adds the same action rule to the QuickFork growth lifecycle plan, making incomplete reports usable only for evidence collection, measurement/crawl/access fixes, gap documentation, or independent product lifecycle work.
• Documents the action-ready evidence requirements: evaluated route or surface, evidence window, production crawlability, GA4 activation data, Search Console query-page evidence, AI-answer observations, and claim hygiene review.

Functional Points

• Stops Codex from using an incomplete SEO/GEO supervisor report to expand landing pages, change SEO/GEO priorities, set pricing, publish product claims, choose productization, or declare demand.
• Keeps the current SEO/GEO workbook/report as P0 measurement infrastructure until the evidence gate passes.
• Preserves allowed next actions when evidence is incomplete: collect missing evidence, fix measurement/crawl/access issues, document gaps, or continue product work whose priority is independent of the report.

Verification

• git diff --check
• Repo docs only; no runtime behavior changed.

Obsidian

• Mirrored the decision in the local Obsidian note: QuickFork/SEO Growth/2026-06-01 QuickFork Cold Start Launch Growth Iteration.md under 2026-06-04 Evidence-Gated Report Use Decision.