Documentation that points where the documentation is

The engine documentation, the staged plan, the session handoff and the project
rules are on the wiki now. What is left here is what ships with the engine:
README, LICENSE, install.sh, and this changelog.

The doc comments in ui/panel.rs, ui/routing.rs and editor/assets.rs named
PLAN.md and docs/scripting.md by path; one of them was a markdown link four
directories up, which had stopped resolving the moment the file moved. They
name the wiki page instead. Cargo.toml's platform comment and the .gitignore
note follow.

A changelog, starting now rather than reconstructed. Oxide stays at 0.1.0: the
version is already in Cargo.toml and Phase 1 runs to Stage 16, so the alpha
phase is where it actually is.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

editor/src/assets.rs

@@ -96,7 +96,7 @@ pub fn seed_default_font(project_assets_dir: &Path) -> std::io::Result<bool> {
 /// The `.rhai` source the "New Script" button writes, personalised with the
 /// script's file stem so the Console output identifies which script speaks.
 ///
-/// Kept to the two lifecycle hooks `docs/scripting.md` teaches first; the
+/// Kept to the two lifecycle hooks the wiki's Scripting page teaches first; the
 /// `update` body ships commented out so a freshly created script visibly runs
 /// (the `init` print) without moving anything until the author opts in.
 pub fn script_template(stem: &str) -> String {