fix(api): validate annotation list pagination query

[WOLIKIMCHENG]

Summary

Fixes #36805

Validate GET /v1/apps/annotations query parameters with a Pydantic query model instead of relying on Flask request.args.get(..., type=int) fallback behavior.

This makes invalid explicit page and limit values fail validation instead of silently using defaults, while preserving the existing default pagination values and valid numeric string support. The query model is also used to document Swagger query parameters.

Screenshots

Before	After
N/A	N/A

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

[github-actions]

Pyrefly Type Coverage

Metric	Base	PR	Delta
Type coverage	45.74%	45.75%	+0.01%
Strict coverage	45.27%	45.28%	+0.01%
Typed symbols	24,621	24,633	+12
Untyped symbols	29,512	29,512	0
Modules	2760	2760	0