docs(component-developer): document options.encryption_hint for JSON editor fields

[natocTo]

Summary

Documents options.encryption_hint, the new component-schema option shipped in keboola/ui#7627 (Linear UT-4836), in the build-component-ui UI-elements reference so Component Factory authors find the opt-out instead of reporting the hint as a component bug.

A format: editor field in application/json mode stores the parsed JSON, so a #-prefixed key inside it really is encrypted on save — regardless of the declared type. Where the JSON is not Keboola configuration (a vendor filter tree, a payload template), the note advertises an action the component cannot use. "options": { "encryption_hint": false } hides the note; encryption behaviour is unchanged.

• references/ui-elements.md — one row in Editor Options, one bullet under Code Editor Modes.
• Patch version bump of component-developer in the plugin manifest and marketplace.

Platform-side docs (Supported Options table): keboola/developers-docs#409

Link to Devin session: https://app.devin.ai/sessions/bad65a351c774d9d9d23e7684c7c68ac
Requested by: @natocTo

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[linear-code]

UT-4836