Implement admin ports and system settings management

- Port CRUD: list, create, update with branding, currency, timezone
- System settings: upsert key-value pairs per port with known settings UI
  (AI feature flags, invoice discount, pipeline weights, berth rules)
- Settings manager with toggle switches, number inputs, and JSON editors
- Replace both stub pages with real implementations

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib/services/settings.service.ts

@@ -0,0 +1,107 @@
+import { and, eq, isNull } from 'drizzle-orm';
+
+import { db } from '@/lib/db';
+import { systemSettings } from '@/lib/db/schema';
+import { createAuditLog } from '@/lib/audit';
+import { NotFoundError } from '@/lib/errors';
+import { emitToRoom } from '@/lib/socket/server';
+
+interface AuditMeta {
+  userId: string;
+  portId: string;
+  ipAddress: string;
+  userAgent: string;
+}
+
+export async function listSettings(portId: string) {
+  // Get port-specific settings
+  const portSettings = await db
+    .select()
+    .from(systemSettings)
+    .where(eq(systemSettings.portId, portId))
+    .orderBy(systemSettings.key);
+
+  // Get global settings (portId is null)
+  const globalSettings = await db
+    .select()
+    .from(systemSettings)
+    .where(isNull(systemSettings.portId))
+    .orderBy(systemSettings.key);
+
+  return { portSettings, globalSettings };
+}
+
+export async function getSetting(key: string, portId: string) {
+  // Try port-specific first, fall back to global
+  const setting = await db.query.systemSettings.findFirst({
+    where: and(eq(systemSettings.key, key), eq(systemSettings.portId, portId)),
+  });
+  if (setting) return setting;
+
+  const global = await db.query.systemSettings.findFirst({
+    where: and(eq(systemSettings.key, key), isNull(systemSettings.portId)),
+  });
+  return global ?? null;
+}
+
+export async function upsertSetting(key: string, value: unknown, portId: string, meta: AuditMeta) {
+  const existing = await db.query.systemSettings.findFirst({
+    where: and(eq(systemSettings.key, key), eq(systemSettings.portId, portId)),
+  });
+
+  if (existing) {
+    await db
+      .update(systemSettings)
+      .set({ value, updatedBy: meta.userId, updatedAt: new Date() })
+      .where(and(eq(systemSettings.key, key), eq(systemSettings.portId, portId)));
+  } else {
+    await db.insert(systemSettings).values({
+      key,
+      value,
+      portId,
+      updatedBy: meta.userId,
+    });
+  }
+
+  void createAuditLog({
+    userId: meta.userId,
+    portId,
+    action: existing ? 'update' : 'create',
+    entityType: 'setting',
+    entityId: key,
+    oldValue: existing ? { value: existing.value } : undefined,
+    newValue: { value },
+    ipAddress: meta.ipAddress,
+    userAgent: meta.userAgent,
+  });
+
+  emitToRoom(`port:${portId}`, 'system:alert', {
+    alertType: 'setting:updated',
+    message: `Setting "${key}" updated`,
+    severity: 'info',
+  });
+
+  return { key, value, portId };
+}
+
+export async function deleteSetting(key: string, portId: string, meta: AuditMeta) {
+  const existing = await db.query.systemSettings.findFirst({
+    where: and(eq(systemSettings.key, key), eq(systemSettings.portId, portId)),
+  });
+  if (!existing) throw new NotFoundError('Setting');
+
+  await db
+    .delete(systemSettings)
+    .where(and(eq(systemSettings.key, key), eq(systemSettings.portId, portId)));
+
+  void createAuditLog({
+    userId: meta.userId,
+    portId,
+    action: 'delete',
+    entityType: 'setting',
+    entityId: key,
+    oldValue: { value: existing.value },
+    ipAddress: meta.ipAddress,
+    userAgent: meta.userAgent,
+  });
+}