Position ContextCanopy as portable AI context

[YusenZhang0601]

Outcome

Centers the public project on its clearest user problem: switching or adding AI agents without losing durable personal context.

Change

• rewrites both homepage READMEs around the switching tax, portable context contract, concrete handoff, honest limits, competitive landscape, FAQ, and roadmap
• adds a root Agent entry so the documented agent-assisted setup has a real discovery surface
• aligns package, plugin, contribution, and feature-request metadata with portability and migration
• keeps provider-native one-click import explicitly on the roadmap rather than overclaiming it

Evidence

• npm test
• npm run smoke
• Node syntax checks
• npm audit --audit-level=low (0 vulnerabilities)
• npm pack --dry-run
• local Markdown link check
• GitHub Markdown render check
• public/private path and secret scan

Boundaries

No personalized Vault data, private paths, credentials, or core runtime behavior changed. Real host installation still requires a fresh-session Doctor verification.