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/projects.md

@@ -0,0 +1,85 @@
+# Project System
+
+`oxide_engine::project` defines what a game is, on disk: a **project**. A project
+is a root directory containing a project file plus a defined folder layout. The
+format lives in the engine (not the editor) because the exported runtime and the
+Stage-16 packer read it too — the editor just adds the create/open/save UI.
+
+## Layout
+
+```
+my-game/
+├── project.oxide      # the project file (RON)
+├── scenes/            # scene files
+├── assets/            # meshes, textures, audio, …
+└── scripts/           # game scripts
+```
+
+The project file records the project name, the engine version it was saved with,
+the enabled [modules](modules.md), and per-project settings.
+
+## Create, open, save
+
+```rust
+use oxide_engine::project::Project;
+
+// Scaffold a new project (creates the folders + project file).
+let mut project = Project::create("/path/to/my-game", "My Game")?;
+
+project.enable_module("render");
+project.save()?;
+
+// Reopen later — by directory or by the project file path.
+let project = Project::open("/path/to/my-game")?;
+assert_eq!(project.name(), "My Game");
+assert!(project.is_module_enabled("render"));
+# Ok::<(), oxide_engine::project::ProjectError>(())
+```
+
+Path helpers (`scenes_dir()`, `assets_dir()`, `scripts_dir()`,
+`project_file_path()`) resolve locations against the root. `create` refuses to
+overwrite an existing project; `open` reports `NotFound` when there is no project
+file.
+
+## Settings storage
+
+Per-project settings are stored as **opaque per-section RON blobs** keyed by
+section name, which keeps the project format independent of any particular
+settings schema:
+
+```rust
+# use oxide_engine::project::Project;
+# let mut project = Project::create(std::env::temp_dir().join("oxide_doc_proj"), "x").unwrap();
+project.set_settings_section("editor", "(theme:\"dark\")");
+assert_eq!(project.settings_section("editor"), Some("(theme:\"dark\")"));
+```
+
+The typed settings framework serializes its sections to and from these strings,
+so a section round-trips through the project file without this module knowing the
+section's shape.
+
+## Recent projects
+
+`RecentProjects` is a small most-recently-used list, persisted globally as an
+editor preference (not inside any project). It de-duplicates and caps:
+
+```rust
+use oxide_engine::project::RecentProjects;
+
+let mut recent = RecentProjects::new(10);
+recent.record("/path/to/my-game");
+// recent.save("~/.config/oxide/recent.ron")?; / RecentProjects::load(...)
+assert_eq!(recent.entries().len(), 1);
+```
+
+## Who consumes this
+
+| Consumer | Stage | Use |
+|----------|-------|-----|
+| Editor | 6 | New/Open/Save Project UI, recent list, Project panel/asset browser |
+| File watcher | 6 | watches `scenes/`, `assets/`, `scripts/` for live reload |
+| Settings framework | 6 | persists per-project sections into the project file |
+| Exported runtime / packer | 16 | reads the layout + enabled modules to bundle the game |
+
+[`Project`]: ../engine/src/project.rs
+[`RecentProjects`]: ../engine/src/project.rs