feat: add database schema, migrations, and API endpoints for span annotations

- Add span_label_types and span_annotations tables to schema
- Seed default span label types (bull_flag, bear_flag, etc.)
- Implement CRUD API endpoints for span label types
- Implement CRUD API endpoints for span annotations
- Add time swap validation in POST endpoint (start_time <= end_time)

src/lib/db/schema.ts

@@ -38,3 +38,28 @@ export const annotations = sqliteTable('annotations', {
   color: text('color').default('#3b82f6'), // hex color code
   created_at: integer('created_at').notNull(),
 });
+
+export const spanLabelTypes = sqliteTable('span_label_types', {
+  id: integer('id').primaryKey({ autoIncrement: true }),
+  name: text('name').notNull().unique(), // internal name (e.g., 'bull_flag')
+  display_name: text('display_name').notNull(), // UI label (e.g., 'Bull Flag')
+  color: text('color').notNull(), // hex color for rectangle fill
+  hotkey: text('hotkey'), // keyboard shortcut (e.g., '1')
+  is_active: integer('is_active').notNull().default(1), // 1 = active, 0 = inactive
+  sort_order: integer('sort_order').notNull().default(0), // display order
+  created_at: integer('created_at').notNull(),
+});
+
+export const spanAnnotations = sqliteTable('span_annotations', {
+  id: integer('id').primaryKey({ autoIncrement: true }),
+  chart_id: integer('chart_id').notNull().references(() => charts.id),
+  start_time: integer('start_time').notNull(), // Unix timestamp of first candle
+  end_time: integer('end_time').notNull(), // Unix timestamp of last candle
+  label: text('label').notNull(), // pattern name referencing span_label_types.name
+  confidence: integer('confidence'), // 1-5 scale, nullable
+  outcome: text('outcome'), // 'win'|'loss'|'breakeven'|null
+  notes: text('notes'), // free-text, nullable
+  sub_spans: text('sub_spans'), // JSON array of sub-span objects, nullable
+  color: text('color').notNull().default('#2196F3'), // hex color
+  created_at: integer('created_at').notNull(),
+});

src/lib/db/seed-span-label-types.ts

@@ -0,0 +1,82 @@
+import { db } from './index';
+import { spanLabelTypes } from './schema';
+
+export async function seedSpanLabelTypes() {
+  const now = Math.floor(Date.now() / 1000);
+
+  const defaultTypes = [
+    {
+      name: 'bull_flag',
+      display_name: 'Bull Flag',
+      color: '#4CAF50',
+      hotkey: '1',
+      is_active: 1,
+      sort_order: 1,
+      created_at: now,
+    },
+    {
+      name: 'bear_flag',
+      display_name: 'Bear Flag',
+      color: '#F44336',
+      hotkey: '2',
+      is_active: 1,
+      sort_order: 2,
+      created_at: now,
+    },
+    {
+      name: 'head_and_shoulders',
+      display_name: 'Head and Shoulders',
+      color: '#9C27B0',
+      hotkey: '3',
+      is_active: 1,
+      sort_order: 3,
+      created_at: now,
+    },
+    {
+      name: 'double_bottom',
+      display_name: 'Double Bottom',
+      color: '#2196F3',
+      hotkey: '4',
+      is_active: 1,
+      sort_order: 4,
+      created_at: now,
+    },
+    {
+      name: 'wedge_up',
+      display_name: 'Wedge Up',
+      color: '#FF9800',
+      hotkey: '5',
+      is_active: 1,
+      sort_order: 5,
+      created_at: now,
+    },
+    {
+      name: 'wedge_down',
+      display_name: 'Wedge Down',
+      color: '#FF5722',
+      hotkey: '6',
+      is_active: 1,
+      sort_order: 6,
+      created_at: now,
+    },
+    {
+      name: 'custom',
+      display_name: 'Custom',
+      color: '#607D8B',
+      hotkey: '7',
+      is_active: 1,
+      sort_order: 7,
+      created_at: now,
+    },
+  ];
+
+  // Check if types already exist
+  const existing = await db.select().from(spanLabelTypes);
+  
+  if (existing.length === 0) {
+    await db.insert(spanLabelTypes).values(defaultTypes);
+    console.log('Seeded default span label types');
+  } else {
+    console.log('Span label types already exist, skipping seed');
+  }
+}