[WIP] Review WARNINGS and SECURITY wording for accuracy

[Copilot]

• Review all WARNING and SECURITY wording across docs for truthfulness and tone
• Soften final-warning.md title and framing (renamed "FINAL WARNING" → "Before You Begin")
• Add context to warning-blast-radius.md that capabilities are standard GitHub Actions runner properties, not unique to this project
• Add context to security-assessment.md executive summary about platform defaults
• Soften README.md callout to "Before You Begin" docs
• Update cross-references in CONTRIBUTING.md, CODE_OF_CONDUCT.md, index.md, the-four-laws-of-ai.md, incident-response.md
• Verify all changes are truthful and not unnecessarily alarming

Summary of changes

All WARNING and SECURITY wording reviewed for truthfulness and tone. Key changes:

• "FINAL WARNING" → "Before You Begin" — welcoming instead of alarming
• "Blast Radius Analysis" → "Capabilities Analysis" — descriptive instead of scary
• "⚠️ WARNING:" bullets → "Things to Keep in Mind" — same content, calmer presentation
• "🔴 CRITICAL" → "🔴 High priority" in summary tables — less militaristic severity language
• Added context notes explaining that most documented capabilities (root access, network egress, Docker) are standard GitHub Actions runner properties, not unique to this project
• Security assessment "Bottom Line" reframed to be informative rather than alarming, pointing to hardening recommendations
• All factual content preserved — nothing removed, only reframed

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