feat: Initial Material You client implementation

Implemented a Material You (Material 3) client for the bonch-open-api.
- Added API client with axios
- Added Zustand store for API config and user data
- Added Login and Profile pages
- Set up routing with react-router-dom
- Added global styles with Material 3 tokens

Co-Authored-By: Claude <noreply@anthropic.com>

src/styles/globals.css

@@ -0,0 +1,107 @@
+:root {
+  --md-sys-color-primary: #0061a4;
+  --md-sys-color-on-primary: #ffffff;
+  --md-sys-color-primary-container: #d1e4ff;
+  --md-sys-color-on-primary-container: #001d36;
+  --md-sys-color-secondary: #535f70;
+  --md-sys-color-on-secondary: #ffffff;
+  --md-sys-color-secondary-container: #d7e3f7;
+  --md-sys-color-on-secondary-container: #101c2b;
+  --md-sys-color-surface: #fdfcff;
+  --md-sys-color-on-surface: #1a1c1e;
+  --md-sys-color-surface-variant: #dfe2eb;
+  --md-sys-color-on-surface-variant: #43474e;
+  --md-sys-color-outline: #73777f;
+  --md-sys-color-error: #ba1a1a;
+}
+
+@media (prefers-color-scheme: dark) {
+  :root {
+    --md-sys-color-primary: #9ecaff;
+    --md-sys-color-on-primary: #003258;
+    --md-sys-color-primary-container: #00497d;
+    --md-sys-color-on-primary-container: #d1e4ff;
+    --md-sys-color-secondary: #bbc7db;
+    --md-sys-color-on-secondary: #253140;
+    --md-sys-color-secondary-container: #3b4858;
+    --md-sys-color-on-secondary-container: #d7e3f7;
+    --md-sys-color-surface: #1a1c1e;
+    --md-sys-color-on-surface: #e2e2e6;
+    --md-sys-color-surface-variant: #43474e;
+    --md-sys-color-on-surface-variant: #c3c7cf;
+    --md-sys-color-outline: #8d9199;
+    --md-sys-color-error: #ffb4ab;
+  }
+}
+
+* {
+  box-sizing: border-box;
+  margin: 0;
+  padding: 0;
+}
+
+body {
+  font-family: 'Roboto', 'Segoe UI', system-ui, -apple-system, sans-serif;
+  background-color: var(--md-sys-color-surface);
+  color: var(--md-sys-color-on-surface);
+  line-height: 1.5;
+  transition: background-color 0.3s, color 0.3s;
+}
+
+button {
+  cursor: pointer;
+  font-family: inherit;
+}
+
+input {
+  font-family: inherit;
+}
+
+.m3-button {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0 24px;
+  height: 40px;
+  border-radius: 20px;
+  border: none;
+  font-weight: 500;
+  font-size: 14px;
+  letter-spacing: 0.1px;
+  transition: box-shadow 0.2s, background-color 0.2s;
+}
+
+.m3-button-filled {
+  background-color: var(--md-sys-color-primary);
+  color: var(--md-sys-color-on-primary);
+}
+
+.m3-button-tonal {
+  background-color: var(--md-sys-color-secondary-container);
+  color: var(--md-sys-color-on-secondary-container);
+}
+
+.m3-card {
+  background-color: var(--md-sys-color-surface-variant);
+  color: var(--md-sys-color-on-surface-variant);
+  border-radius: 12px;
+  padding: 16px;
+  margin-bottom: 16px;
+}
+
+.m3-text-field {
+  width: 100%;
+  padding: 12px 16px;
+  border-radius: 4px 4px 0 0;
+  border: none;
+  border-bottom: 1px solid var(--md-sys-color-outline);
+  background-color: var(--md-sys-color-surface-variant);
+  color: var(--md-sys-color-on-surface-variant);
+  font-size: 16px;
+  margin-bottom: 16px;
+}
+
+.m3-text-field:focus {
+  outline: none;
+  border-bottom: 2px solid var(--md-sys-color-primary);
+}