chg: make yaml ruletype field optional

[fukusuket]

What Changed

• Make yaml ruletype field optional
• Related: fix: improve logging for invalid rule #1641

Evidence

Integration-Test

• https://github.com/Yamato-Security/hayabusa/actions/runs/15083650408

I’d appreciate it if you could check it when you have time🙏

[Copilot]

Pull Request Overview

This PR updates the YAML rule format to make the ruletype field optional.

• Removed ruletype from the list of required keys.
• Eliminated the ruletype-specific validation block.
• Simplified rule format checks in the YAML processing function.

Comments suppressed due to low confidence (2)

src/yaml.rs:824

• [nitpick] With ruletype now optional, consider adding a conditional check to validate its value (if provided) to ensure consistency with accepted types (e.g., "hayabusa" or "sigma").

"ruletype",

src/yaml.rs:839

• [nitpick] Ensure that the removal of the ruletype validation logic is aligned with the overall schema strategy; if ruletype is supplied by users, consider documenting the expected outcome when its value does not meet the typical standards.

match key {

[YamatoSecurity]

@fukusuket LGTM! Thanks so much!