Import Oxide engine (Stages 0–10) under MIT license

Full project snapshot migrated to new Gitea remote without history:
engine, editor, physics, script, examples, tests, docs, and assets.
Relicensed from GPLv3 to MIT and updated repo URLs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/settings.md

@@ -0,0 +1,70 @@
+# Settings & Preferences Framework
+
+`oxide_engine::settings` is the engine's unified, serialized configuration store.
+The engine, the editor, and every module register typed **sections**; the
+framework persists them all to RON and restores them — without any central code
+knowing the sections' shapes. It is the backbone of the editor's Preferences
+window and of per-module settings.
+
+## Sections
+
+A section is any plain `serde`-serializable struct with a `Default`. Register it
+once under a name and the store owns a typed instance:
+
+```rust
+use oxide_engine::settings::Settings;
+use serde::{Serialize, Deserialize};
+
+#[derive(Serialize, Deserialize, Default)]
+struct EditorPrefs { theme: String, grid: bool }
+
+let mut settings = Settings::new();
+settings.register::<EditorPrefs>("editor");
+
+// Typed read/write.
+settings.get_mut::<EditorPrefs>("editor").unwrap().theme = "dark".into();
+assert_eq!(settings.get::<EditorPrefs>("editor").unwrap().theme, "dark");
+```
+
+`set` replaces a section's value (only if the registered type matches), and
+`reset` returns it to `Default`. Accessing a section as the wrong type returns
+`None` rather than panicking.
+
+## Persisting
+
+Every section serializes to a `name → RON` map via `export`, and `import` loads
+matching sections back. This map is exactly the shape a
+[`Project`](projects.md) stores, so per-project settings round-trip through the
+project file:
+
+```rust
+# use oxide_engine::settings::Settings;
+# use serde::{Serialize, Deserialize};
+# #[derive(Serialize, Deserialize, Default)] struct EditorPrefs { theme: String }
+# let mut settings = Settings::new();
+# settings.register::<EditorPrefs>("editor");
+let saved = settings.export();          // BTreeMap<String, String>
+
+let mut restored = Settings::new();
+restored.register::<EditorPrefs>("editor");
+restored.import(&saved);                // matching sections restored
+```
+
+`import` is deliberately lenient: an **unknown** section (e.g. one owned by a
+disabled module) is ignored, and a **malformed** section is skipped, leaving its
+current value. This means a project saved with a module enabled still opens
+cleanly with that module disabled, and vice-versa.
+
+## How the layers fit together
+
+| Scope | Lives where | Persisted to |
+|-------|-------------|--------------|
+| Engine preferences (render/quality defaults) | a `Settings` section | global prefs file / project |
+| Editor preferences (theme, layout, shortcuts) | a `Settings` section | global editor prefs file |
+| Per-module settings | each module registers a section | the [project](projects.md) it's enabled in |
+
+`Project` stores the per-project subset (`set_settings_section` /
+`settings_section` hold the same RON blobs `export`/`import` produce). The editor
+keeps its global preferences in a separate file using the same `Settings` API.
+
+[`Settings`]: ../engine/src/settings.rs