feat(themes): Solarized and One theme plugins (#92)

Solarized Light/Dark and One Light/Dark ship as theme plugins (plugins/theme-solarized, plugins/theme-one) with complete UI tokens, editor schemes and terminal colours, and the original palettes' MIT notices. Installing a plugin now also copies its LICENSE/NOTICE/COPYING.

Theme handling that benefits every plugin theme:
- The last plugin theme is restored before first paint (splash, workbench); the native window background follows the theme.
- HSL / color-mix() / var() colours are resolved to RGB for native windows, the Settings window and Mermaid.
- Mermaid, the terminal and editor schemes follow switches between two themes of the same kind.
- An explicitly chosen editor scheme wins over a plugin theme's editor colours.

Supersedes #85.

Co-authored-by: bghtyu <[email protected]>
Claude-Session: https://claude.ai/code/session_01VUYsdXA2nkF5v6zsC93dpn

scripts/theme/theme.test.ts

@@ -1,4 +1,4 @@
-import { readFileSync } from "node:fs";
+import { existsSync, readdirSync, readFileSync } from "node:fs";
 import { describe, expect, it } from "vitest";
 import {
   convertIcls,
@@ -77,6 +77,73 @@ describe("theme plugin template", () => {
   });
 });
 
+/** Theme packages in plugins/: every theme they contribute, with its editor scheme. */
+function pluginThemes() {
+  return readdirSync("plugins", { withFileTypes: true })
+    .filter((d) => d.isDirectory() && existsSync(`plugins/${d.name}/plugin.toml`))
+    .flatMap((d) => {
+      const dir = `plugins/${d.name}`;
+      const manifest = read(`${dir}/plugin.toml`);
+      return manifest
+        .split("[[contributes.themes]]")
+        .slice(1)
+        .map((entry) => ({
+          dir,
+          manifest,
+          path: /^path\s*=\s*"([^"]+)"/m.exec(entry)?.[1],
+          scheme: /^editor-scheme\s*=\s*"([^"]+)"/m.exec(entry)?.[1],
+        }));
+    });
+}
+
+describe("theme plugins in plugins/", () => {
+  const themes = pluginThemes();
+
+  it("include Solarized and One, light and dark", () => {
+    expect(themes.map((t) => `${t.dir}/${t.path}`)).toEqual(
+      expect.arrayContaining([
+        "plugins/theme-solarized/themes/solarized-light.theme.json",
+        "plugins/theme-solarized/themes/solarized-dark.theme.json",
+        "plugins/theme-one/themes/one-light.theme.json",
+        "plugins/theme-one/themes/one-dark.theme.json",
+      ]),
+    );
+  });
+
+  it.each(themes.map((t) => [`${t.dir}/${t.path}`, t] as const))(
+    "%s sets every UI token and its scheme every editor token",
+    (_name, t) => {
+      // A failure here means tokens.css gained (or lost) a themeable token: add it to the theme too.
+      expect(t.path && t.scheme, "theme and editor-scheme paths").toBeTruthy();
+      expect(t.manifest).not.toMatch(/^wasm\s*=/m);
+      const ui = JSON.parse(stripJsonComments(read(`${t.dir}/${t.path}`))) as {
+        id: string;
+        name: string;
+        kind: string;
+        tokens: Record<string, string>;
+      };
+      const ed = JSON.parse(stripJsonComments(read(`${t.dir}/${t.scheme}`))) as { tokens: Record<string, string> };
+      expect(ui.id).toMatch(/^[a-z0-9][a-z0-9._-]*$/);
+      expect(ui.name.trim()).not.toBe("");
+      expect(["light", "dark"]).toContain(ui.kind);
+      expect(sorted(Object.keys(ui.tokens))).toEqual(sorted(sets.ui));
+      expect(sorted(Object.keys(ed.tokens))).toEqual(sorted(sets.scheme));
+      for (const [k, v] of Object.entries({ ...ui.tokens, ...ed.tokens })) {
+        expect(/[;{}<>\\\n]|url\(|image\(/i.test(v), `${k}: ${v}`).toBe(false);
+        // var() may only point at tokens the IDE defines.
+        for (const [, ref] of v.matchAll(/var\((--[a-z0-9-]+)/g)) expect(css, `${k} → ${ref}`).toContain(`${ref}:`);
+      }
+    },
+  );
+
+  it("ship the licence of the palettes they port", () => {
+    for (const dir of new Set(themes.map((t) => t.dir))) {
+      if (dir === "plugins/theme-solarized" || dir === "plugins/theme-one")
+        expect(read(`${dir}/LICENSE`), dir).toContain("MIT License");
+    }
+  });
+});
+
 describe("IntelliJ theme import", () => {
   const themeJson = `{
     // comment