feat(ci): Add Forgejo CI/CD pipeline for linting and building

- Automated linting with rustfmt and clippy
- Automated building and testing
- Automated Docker image builds
- Clippy and rustfmt configuration files

backend/rustfmt.toml

@@ -0,0 +1,15 @@
+# Rustfmt configuration
+
+max_width = 100
+hard_tabs = false
+tab_spaces = 4
+newline_style = "Unix"
+use_small_heuristics = "Default"
+reorder_imports = true
+reorder_modules = true
+remove_nested_parens = true
+edition = "2021"
+merge_derives = true
+use_try_shorthand = true
+use_field_init_shorthand = true
+force_explicit_abi = true