chore: fix content quality warnings from new guardrails

[oskarth]

The new AI content guardrails (#58) found existing issues in content:

Summary

• 37 structural warnings (schema/frontmatter)
• 39 terminology inconsistencies
• ~200 prose warnings (passive voice, wordy phrases, marketing language)

Terminology Issues (39)

Most common:

• "ZK proof" → "zero-knowledge proof" (20+ instances)
• "zkSNARK/zkSTARK" → "zk-SNARK/zk-STARK" (6 instances)
• "data availability" → "Data Availability" (2 instances)

Run npm run check-terms for full list.

Schema/Structure Warnings (37)

• Broken internal links (files renamed/moved)
• Non-standard maturity values in vendors
• Frontmatter fields not matching schema

Run npm run validate for full list.

Prose Warnings (~200)

• 174 passive voice
• 114 marketing language ("only", etc.)
• 57 terminology casing

Run npm run lint:vale for full list.

Recommended Approach

1. Fix terminology issues first (highest signal)
2. Fix broken links
3. Address schema warnings
4. Prose warnings are lower priority (many are stylistic)

Related: #58