fix(forms): honor declared GET and POST methods

[ShivamB25]

Summary

• Submit HTML forms using their declared HTTP method instead of always encoding values into a GET URL.
• Preserve explicit ports when resolving root-relative form actions.
• Exclude non-submit controls from form actions.

Changes

• Send GET form values as query parameters and POST values as URL-encoded request bodies.
• Reuse navigation result handling for form responses.
• Add local request-capture tests for GET and POST plus parser regressions.

Verification

• cargo test
• cargo clippy --all-targets -- -D warnings

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