Restructure into pnpm monorepo with game shell, docs, and SpacetimeDB backend

- Restructure flat static prototype into pnpm workspace monorepo
- apps/game: playable shell with R3F 3D scene, HUD, SpacetimeDB connection
- apps/docs: design docs and prototypes
- apps/site: landing page
- packages/ui: shared Button and Panel primitives
- services/spacetimedb: backend module (9 tables, 11 reducers)
- Archive legacy static files to archive/legacy-static/
- Game loop: connect, undock, target, approach, dock, mine, sell
- Add pnpm-workspace.yaml, tsconfig.base.json, spacetime.json

packages/ui/src/styles.css

@@ -0,0 +1,75 @@
+@theme {
+  --color-bg: #080c14;
+  --color-bg-subtle: #0b1120;
+  --color-surface: #0f1623;
+  --color-surface-raised: #162032;
+  --color-surface-hover: #1c2d45;
+  --color-fg: #d4dce8;
+  --color-fg-bright: #f1f5f9;
+  --color-fg-dim: #94a3b8;
+  --color-muted: #5a6b82;
+  --color-border: #1c2a3f;
+  --color-border-light: #253550;
+  --color-accent: #f0a030;
+  --color-accent-hover: #fbbf24;
+  --color-cyan: #22d3ee;
+  --color-red: #ef4444;
+  --color-green: #22c55e;
+  --color-purple: #a78bfa;
+
+  --font-display: "SF Pro Display", -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
+  --font-body: "SF Pro Text", -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
+  --font-mono: "JetBrains Mono", "Fira Code", ui-monospace, Menlo, monospace;
+}
+
+@layer base {
+  :root {
+    --bg: var(--color-bg);
+    --bg-subtle: var(--color-bg-subtle);
+    --surface: var(--color-surface);
+    --surface-raised: var(--color-surface-raised);
+    --surface-hover: var(--color-surface-hover);
+    --fg: var(--color-fg);
+    --fg-bright: var(--color-fg-bright);
+    --fg-dim: var(--color-fg-dim);
+    --muted: var(--color-muted);
+    --border: var(--color-border);
+    --border-light: var(--color-border-light);
+    --accent: var(--color-accent);
+    --accent-hover: var(--color-accent-hover);
+    --cyan: var(--color-cyan);
+    --red: var(--color-red);
+    --green: var(--color-green);
+    --purple: var(--color-purple);
+  }
+
+  *, *::before, *::after {
+    box-sizing: border-box;
+  }
+
+  html {
+    font-size: 14px;
+    -webkit-font-smoothing: antialiased;
+    -moz-osx-font-smoothing: grayscale;
+    text-rendering: optimizeLegibility;
+  }
+
+  body {
+    margin: 0;
+    min-height: 100vh;
+    background: var(--bg);
+    color: var(--fg);
+    font-family: var(--font-body);
+    line-height: 1.6;
+  }
+
+  a {
+    color: inherit;
+    text-decoration: none;
+  }
+
+  button,
+  input {
+    font: inherit;
+  }
+}