feat: schelet gateway FastAPI (API v1 + worker + dashboard + SQLite WAL)

Structura repo conform plan.md sect. 4, booteaza cu /healthz verde:
- app/main.py: FastAPI (lifespan init_db), /healthz (worker viu + last login + queue), /metrics
- app/api/v1: POST /v1/prezentari (enqueue + dedup idempotency UNIQUE), GET prezentari/{id}, nomenclator, mapari
- app/rar_client.py: client RAR real (login/JWT, nomenclator, postPrezentare, getFinalizate) cu User-Agent obligatoriu (fix WAF 403)
- app/worker: proces separat, claim atomic BEGIN IMMEDIATE, heartbeat, login+send (send dezactivat by default)
- app/web: dashboard Jinja2+HTMX (coada, banner alerta blocate, worker viu/mort, stari empty)
- app/db.py + schema.sql: SQLite WAL, tabele accounts/api_keys/operations_mapping/nomenclator_rar/submissions/worker_heartbeat
- app/idempotency.py + payload.py: hash continut canonic + builder payload (status FINALIZATA, fara tipPrestatie)
- Dockerfile + docker-compose.yml (api+worker, volum SQLite persistent, restart:always)
- tools/import_dbf.py: stub T5

Verificat live: login prin rar_client OK (token 259), nomenclator 18 coduri, worker heartbeat -> /healthz worker_alive=True.
Ramas: T3 validare Pydantic, T4 snapshot payload, T2 reconciliere/retry worker, T5 import DBF, auth API-key, middleware redactare creds, criptare PII.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/web/templates/_submissions.html

@@ -0,0 +1,20 @@
+{% if rows %}
+<table>
+  <thead><tr><th>#</th><th>Stare</th><th>idPrezentare</th><th>HTTP RAR</th><th>Retry</th><th>Actualizat</th><th>Motiv</th></tr></thead>
+  <tbody>
+  {% for r in rows %}
+    <tr>
+      <td>{{ r.id }}</td>
+      <td><span class="pill s-{{ r.status }}">{{ r.status }}</span></td>
+      <td>{{ r.id_prezentare or '—' }}</td>
+      <td>{{ r.rar_status_code or '—' }}</td>
+      <td>{{ r.retry_count }}</td>
+      <td class="muted">{{ r.updated_at }}</td>
+      <td class="muted">{{ (r.rar_error or '')[:80] }}</td>
+    </tr>
+  {% endfor %}
+  </tbody>
+</table>
+{% else %}
+<div class="empty">Coada e goala. Trimite o prezentare prin <code>POST /v1/prezentari</code>.</div>
+{% endif %}