Normalize bounded read-tool limits consistently

[vsolano9]

What & why

Current main already sends both shopify_orders and db_query through the same clampInt helper, so the issue’s 1000/-5/NaN examples are no longer raw at the connectors. The remaining hole is numeric fractions and infinities: 1.9 reaches both URLs unchanged, while positive/negative infinity become opposite bounds. This completes the existing centralized clamp contract.

Closes #4

Changes

• default every non-finite limit, including both infinities, to 10
• truncate finite fractional numbers before the existing 1–50 clamp
• state the truncation/clamp behavior in both MCP input schemas
• add connector-level tests that capture the real Shopify and PostgREST URLs and prove both tools receive the same normalized integer
• expose the dependency-free suite through npm test

Validation

• RED: both connectors emitted 1.9; positive infinity became 50 and negative infinity became 1
• npm test — 10/10 pass; repeated successfully 20 consecutive times
• Node 20 test run — 10/10 pass
• npm run typecheck — pass
• fresh npm ci — pass
• npx wrangler deploy --dry-run — pass; no deployment
• git diff --check — pass
• production dependency audit — 0 findings; fresh install reports six existing development dependency advisories; no dependency or lockfile changes

Checklist

• Focused change with a clear description
• Ran format / lint / tests (repository provides typecheck and tests; both pass)
• Updated docs or CHANGELOG if relevant (tool schemas now describe normalization)
• Linked the related issue