feat: Phase 4-5 — demo mode, polish, deploy, and bug fixes

Add demo mode with mock data provider, Docker deployment, Playwright
tests, PostHog analytics, error boundaries, and SEO metadata. Fix
residences API response unwrapping, kanban drag-and-drop with optimistic
updates, trailing slash proxy redirects, and column name mismatches with
Go API.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/api/client.ts

@@ -7,7 +7,7 @@
 // ---------------------------------------------------------------------------
 
 const API_BASE_URL =
-  process.env.NEXT_PUBLIC_API_URL || 'https://mycrib.treytartt.com/api';
+  process.env.NEXT_PUBLIC_API_URL || 'https://casera.treytartt.com/api';
 
 /**
  * Server-only base URL. Falls back to the public one so that server
@@ -45,8 +45,10 @@ export async function apiFetch<T>(
   path: string,
   options: RequestInit = {},
 ): Promise<T> {
-  // Ensure trailing slash (Go API requires it)
-  const normalized = path.endsWith('/') ? path : `${path}/`;
+  // Strip trailing slash for the Next.js proxy URL (Next.js 308-redirects
+  // trailing slashes away by default). The proxy route handler re-adds the
+  // trailing slash when forwarding to the Go API.
+  const normalized = path.endsWith('/') ? path.slice(0, -1) : path;
   const url = `/api/proxy${normalized}`;
 
   const headers: Record<string, string> = {