Add Flask shopping app with Nomad deployment

Flask app serving the Citti shopping list with SQLite persistence,
per-category item addition, dynamic custom categories, photo upload,
and a post-trip price analysis page.

- Port 9756, DATA_DIR env var for persistent volume in Nomad
- Gitea Actions pipeline builds Docker image and deploys via Nomad API
- Makefile targets: run, install, build, push

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

citti.nomad

@@ -0,0 +1,50 @@
+job "citti" {
+  datacenters = ["dc1"]
+  type        = "service"
+
+  group "app" {
+    count = 1
+
+    volume "citti-data" {
+      type      = "host"
+      read_only = false
+      source    = "citti-data"
+    }
+
+    network {
+      port "http" {
+        static = 9756
+      }
+    }
+
+    task "web" {
+      driver = "docker"
+
+      config {
+        image      = "gea.i80.dk/hjess/citti:latest"
+        ports      = ["http"]
+        force_pull = true
+      }
+
+      volume_mount {
+        volume      = "citti-data"
+        destination = "/data"
+        read_only   = false
+      }
+
+      env {
+        DATA_DIR = "/data"
+      }
+
+      resources {
+        cpu    = 200
+        memory = 256
+      }
+
+      service {
+        name = "citti"
+        port = "http"
+      }
+    }
+  }
+}