fix(history): reject fractional page sizes

[JerryNee]

Summary

• make test result --history --page-size reject fractional values before building the request
• keep the existing 1-100 bounds check, but add an integer check for values such as 1.5
• add regression coverage that ensures no request is made for a fractional history page size

Repro

Before this change, testsprite test result test_abc --history --dry-run --page-size 1.5 --output json exited 0 and passed the fractional page size through. After this change it exits 5 with a local VALIDATION_ERROR naming page-size.

Verification

• npm test -- src/commands/test.result.history.spec.ts
• npm run typecheck
• npm run lint
• npm test
• npm run build
• node dist/index.js --output json test result test_abc --history --dry-run --page-size 1.5