feat: add Query and MustQuery for the HTTP QUERY method (RFC 10008)

[thatwasyahya]

What

Adds Query and MustQuery verb helpers for the HTTP QUERY method.

Why

RFC 10008 (Proposed Standard, June 2026) defines QUERY, a safe and idempotent method that carries the query as request content — like GET but with a body, and unlike POST it is safe, idempotent and retryable. It's a good fit for large or structured queries that don't belong in a URL.

What's added

• Request.Query(url) — mirrors Get/Post, sending the QUERY method.
• Request.MustQuery(url) — mirrors MustGet.

No other changes are needed: req already sends the request body for methods other than GET/HEAD/OPTIONS, so client.R().SetBody(...).Query(url) works out of the box.

Tests

Extends TestSendMethods with a QUERY case. go test ./... passes.

[Copilot]

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[imroc]

Automated review (PR Review Loop):

Scope: Adds Query() and MustQuery() methods for the HTTP QUERY method (RFC 10008). Files: request.go (+23 lines), request_test.go (+6 lines). Very small, focused change.

Review:

• Query(url) calls r.Send("QUERY", url) — consistent with existing Get, Head, Post, etc. method patterns. Correct.
• MustQuery panics on error — consistent with existing MustGet, MustPost convention. The comment "should only be used to test without error handling" matches the existing Must* methods.
• Test added in TestSendMethods table — verifies the method is sent as "QUERY". Consistent with existing test structure.
• No changes to modified stdlib, quic-go, or HTTP/2 code.

Note: CI did not run on this branch (fork PR). The code is straightforward and follows existing patterns. Recommend the maintaker trigger CI or do a local build before merge.

No blockers from code review perspective.