Hey, could we add the ability to upload images to Cloudflare R2?

[Yakumo-Yukari]

https://www.cloudflare.com/developer-platform/products/r2/ R2 is a free cloud storage feature, so we can definitely allow users to upload and store images on R2.

[coderabbitai]

A summary of the changes CodeRabbit can apply:

• Add Cloudflare R2 support and a storage abstraction to freedit: create src/storage.rs (R2 + local), add R2 config in src/config.rs, update upload and admin controllers (src/controller/upload.rs, src/controller/admin.rs) and templates (templates/admin_gallery.html) to use generated URLs, update data model (PageAdminGallery struct), add AWS/R2 deps to Cargo.toml, and add docs at docs/R2_INTEGRATION.md.

• Add Cloudflare R2 support and a Storage abstraction by updating Cargo.toml (add aws-config and aws-sdk-s3), extending src/config.rs with an R2Config, adding a new src/storage.rs implementing local/R2 backends (upload/delete/get_url), exporting Storage in src/lib.rs, and modifying src/controller/upload.rs plus templates (templates/gallery.html, templates/upload.html) to use the Storage API (store/delete on R2 when enabled and render external URLs).

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