Add photo copyright & usage clause (EN/MK/SI)

Add a "Photos, images & copyright" card to the Official information
(legal) page in all three languages, plus a short rights/removal note
on the Gallery and Events & Projects pages.

- Clarifies most images are MSOS property or used with permission, and
  that third-party images (Get to know Macedonia/Slovenia, Student
  Welcome Guide) remain their owners' property.
- Requires prior written permission to reuse MSOS's own images.
- Adds a photo-removal / consent-withdrawal path via info@msosorg.com.
- New shared .photo-rights-note style in css/pages/_gallery.css.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

si/projects/index.html

@@ -359,6 +359,7 @@
                 </div>
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         </section>
+        <p class="photo-rights-note">Fotografije z dogodkov na tem spletnem mestu so last MSOS. Prosimo, da jih ne uporabljate brez našega pisnega dovoljenja. Za prošnjo za uporabo ali za odstranitev fotografije, na kateri ste, nam pišite na <a href="mailto:info@msosorg.com">info@msosorg.com</a>. Več na naši strani <a href="../../si/legal/">Uradni podatki</a>.</p>
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