fix: reject zero query limits

[linhongyu510]

Summary

Fixes #2150.

Passing limit=0 currently serializes the value correctly, but the server treats it as an omitted limit and returns its default page size. This is surprising because callers explicitly requested zero results.

This change rejects limit=0 when client-side argument validation is enabled. It preserves the existing low-level wire behavior when validation is explicitly disabled.

Tests

Added regression coverage for:

• rejecting limit=0 with argument validation enabled;
• accepting limit=None and positive limits;
• preserving limit=0 and omitted-limit serialization when validation is disabled.

Validation performed:

• pytest test/collection/test_queries.py test/collection/test_bm25_operator.py -q — 8 passed
• Ruff lint and format checks — passed
• Flake8 — passed
• git diff --check — passed

Compatibility

This is an explicit validation behavior change only for clients using the default validate_arguments=True. Clients that disable validation retain the existing request serialization.

This change was implemented with AI assistance and validated with the tests listed above.

[orca-security-eu]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	SAST	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca

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