chore(ui): refactor workspace to monorepo (#70)

## Summary by Sourcery

Refactor the UI project structure into a pnpm monorepo packages layout
and align tooling and automation with the new paths.

Enhancements:
- Reorganize the UI app from the root ui directory into packages/ui
within a pnpm workspace.
- Update pnpm workspace configuration to include all packages under
packages/*.
- Adjust paths in changeset configuration so the @dropout/ui package
resolves from packages/ui.

Build:
- Update pre-commit configuration paths and arguments to reflect the new
UI location and normalize hook argument formatting.
- Update Dependabot configuration so npm updates target /packages/ui
instead of /ui.

CI:
- Update GitHub Actions workflows to watch packages/** instead of ui/**
and to run frontend tasks from packages/ui.
- Update pnpm cache dependency paths in workflows to use the root
pnpm-lock.yaml.
- Simplify frontend install steps in test workflows to run from the
repository root.

Chores:
- Add a new index.html under packages/ui and remove the old
ui/index.html to match the new project layout.

1 files changed, 78 insertions, 0 deletions

diff --git a/packages/ui/src/stores/game.svelte.ts b/packages/ui/src/stores/game.svelte.ts
new file mode 100644
index 0000000..504d108
--- /dev/null
+++ b/packages/ui/src/stores/game.svelte.ts
@@ -0,0 +1,78 @@
+import { invoke } from "@tauri-apps/api/core";
+import type { Version } from "../types";
+import { uiState } from "./ui.svelte";
+import { authState } from "./auth.svelte";
+import { instancesState } from "./instances.svelte";
+
+export class GameState {
+  versions = $state<Version[]>([]);
+  selectedVersion = $state("");
+
+  constructor() {
+    // Constructor intentionally empty
+    // Instance switching handled in App.svelte with $effect
+  }
+
+  get latestRelease() {
+    return this.versions.find((v) => v.type === "release");
+  }
+
+  async loadVersions(instanceId?: string) {
+    const id = instanceId || instancesState.activeInstanceId;
+    if (!id) {
+      this.versions = [];
+      return;
+    }
+
+    try {
+      this.versions = await invoke<Version[]>("get_versions", {
+        instanceId: id,
+      });
+      // Don't auto-select version here - let BottomBar handle version selection
+      // based on installed versions only
+    } catch (e) {
+      console.error("Failed to fetch versions:", e);
+      uiState.setStatus("Error fetching versions: " + e);
+    }
+  }
+
+  async startGame() {
+    if (!authState.currentAccount) {
+      alert("Please login first!");
+      authState.openLoginModal();
+      return;
+    }
+
+    if (!this.selectedVersion) {
+      alert("Please select a version!");
+      return;
+    }
+
+    if (!instancesState.activeInstanceId) {
+      alert("Please select an instance first!");
+      uiState.setView("instances");
+      return;
+    }
+
+    uiState.setStatus("Preparing to launch " + this.selectedVersion + "...");
+    console.log(
+      "Invoking start_game for version:",
+      this.selectedVersion,
+      "instance:",
+      instancesState.activeInstanceId,
+    );
+    try {
+      const msg = await invoke<string>("start_game", {
+        instanceId: instancesState.activeInstanceId,
+        versionId: this.selectedVersion,
+      });
+      console.log("Response:", msg);
+      uiState.setStatus(msg);
+    } catch (e) {
+      console.error(e);
+      uiState.setStatus("Error: " + e);
+    }
+  }
+}
+
+export const gameState = new GameState();