fix(api): validate property run limits

[rissrice2105-agent]

Summary

• validate property run limit query values as positive integers
• default malformed, fractional, zero, or negative limits to 25
• keep the existing 100 item cap for valid positive limits
• add regression coverage for invalid and oversized limits

Closes #18

Tests

• corepack pnpm install --ignore-scripts
• corepack pnpm --filter @profullstack/threatcrush-web test -- "src/app/api/orgs/[id]/properties/[property_id]/runs/tests/route.test.ts"
• corepack pnpm --filter @profullstack/threatcrush-web build