fix(04-06): five post-deploy fixes

- Middleware (proxy.ts): switch internal API calls to localhost instead of
  request.url — avoids Docker hairpin NAT issues where the container can't
  reach its own external hostname via Traefik
- ProjectRow timer: pass projectId={project.id} to TimerCell so it calls
  startTimer(projectId) directly instead of startTimerForClient(project.id)
- Admin client list: add slug field to ClientWithPayments + show slug link
  when available (falls back to token) — so admins see the human-readable URL
- Analytics contracted: sum projects.accepted_total (authoritative) instead
  of clients.accepted_total (always 0 in multi-project architecture)
- createClient: auto-generate slug from client name at creation time
  (e.g. "Mario Rossi" → "mario-rossi"), with -2/-3 suffix on conflict

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

src/components/admin/ClientRow.tsx

@@ -53,12 +53,12 @@ export function ClientRow({ client }: { client: ClientWithPayments }) {
       </td>
       <td className="py-3 px-4">
         <a
-          href={`/client/${client.token}`}
+          href={`/client/${client.slug || client.token}`}
           target="_blank"
           rel="noopener noreferrer"
           className="text-xs text-[#1A463C] hover:underline font-mono"
         >
-          /client/{client.token.slice(0, 8)}…
+          /client/{(client.slug || client.token).slice(0, 12)}…
         </a>
       </td>
     </tr>

src/components/admin/ProjectRow.tsx

@@ -52,6 +52,7 @@ export function ProjectRow({ project }: { project: ProjectWithPayments }) {
       <td className="py-3 px-4">
         <TimerCell
           clientId={project.id}
+          projectId={project.id}
           activeEntryId={project.activeTimerEntryId}
           activeStartedAt={project.activeTimerStartedAt}
           totalTrackedSeconds={project.totalTrackedSeconds}