feat(prompts): render no-hardcoding agent rule

[andrei-hasna]

Summary

• add the no-brittle-hardcoding rule to the seeded managed global-agent rules standard
• update Codewith and Antigravity render tests/smokes to prove the rule reaches CODEWITH.md and Antigravity .agents/rules output
• bump package metadata and docs for the updated managed prompt standard

Validation

• env -u HASNA_INSTRUCTIONS_API_URL -u HASNA_INSTRUCTIONS_API_KEY bun run typecheck
• env -u HASNA_INSTRUCTIONS_API_URL -u HASNA_INSTRUCTIONS_API_KEY bun test
• env -u HASNA_INSTRUCTIONS_API_URL -u HASNA_INSTRUCTIONS_API_KEY bun run build
• env -u HASNA_INSTRUCTIONS_API_URL -u HASNA_INSTRUCTIONS_API_KEY bun run kit:check
• managed render smoke for codewith and antigravity includes the no-hardcoding rule
• HOME= env -u HASNA_INSTRUCTIONS_API_URL -u HASNA_INSTRUCTIONS_API_KEY bun run check:package-secrets
• gitleaks git --staged --redact --no-banner --no-color .
• gitleaks git --log-opts HEAD~1..HEAD --redact --no-banner --no-color .