fix(cli): reject malformed page number options

[dirtybits]

Summary

agentvouch skill list --page previously used parseInt, silently changing malformed user input: 9.5 became page 9 and 3x became page 3. The CLI now accepts only whitespace-padded positive decimal integers that fit in JavaScript's safe integer range; fractional, partially numeric, signed, scientific-notation, and unsafe integer values produce the existing clear validation error.

This is a focused CLI input-boundary fix: two files, no API, protocol, chain, dependency, or configuration changes.

Test plan

• RED: npm test --workspace @agentvouch/cli -- cli-options.test.ts failed before the implementation because 9.5 was silently accepted as page 9.
• npm test --workspace @agentvouch/cli -- cli-options.test.ts — 10 tests passed.
• npm run test --workspace @agentvouch/cli — 13 files / 77 tests passed.
• npm run typecheck --workspace @agentvouch/cli — passed.
• npm run build --workspace @agentvouch/cli — passed (tsup ESM + declarations).
• npm run format:check — passed.
• npm run lint — passed.
• git diff --check origin/main...HEAD — passed.

Rollback

Revert this commit to restore the prior permissive parseInt behavior; no data or deployed state requires cleanup.

Not verified

• No web build, Vercel deploy, browser, wallet, database, or chain smoke: this is a CLI-only parsing change.