feat(feedback): Fehler-melden-Dialog + ID-kopieren (Stammbaum/Akte/Wurf)

Rechtsklick auf eine Maus im Stammbaum öffnet ein Kontextmenü mit „ID kopieren"
(Clipboard + Toast) und „Fehler melden". Zusätzlich „Fehler melden"-Buttons in
der Rennmausakte und der Wurf-Ansicht. Der Dialog erfasst eine Beschreibung und
sendet sie samt Debug-Kontext (Ansicht, Tier-/Wurf-ID + Name, URL, Zeitstempel,
User-Agent) an POST /feedback; gespeichert in einer neuen Feedback-Tabelle.

Backend: Feedback-Entity (lose nullable GerbilId/LitterId ohne FK), Endpoints
POST/GET /feedback, EF-Migration AddFeedback. Die Tabelle wird vom Import-Ingest
NICHT geleert — Feedback überlebt Re-Ingests (Test deckt das ab).

Tests: FeedbackEndpointTests (persistiert, 400 bei leer, übersteht Ingest-Wipe);
e2e feedback.spec.ts. tsc/eslint/vitest(129)/playwright(6)/dotnet(212) grün.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

GerbilManagerWebAPI/Migrations/20260622131928_AddFeedback.cs

@@ -0,0 +1,47 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace GerbilManagerWebAPI.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddFeedback : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "Feedback",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "uuid", nullable: false),
+                    Message = table.Column<string>(type: "text", nullable: false),
+                    Context = table.Column<string>(type: "text", nullable: false),
+                    GerbilId = table.Column<Guid>(type: "uuid", nullable: true),
+                    LitterId = table.Column<Guid>(type: "uuid", nullable: true),
+                    EntityName = table.Column<string>(type: "text", nullable: true),
+                    Url = table.Column<string>(type: "text", nullable: true),
+                    ClientTimestamp = table.Column<DateTimeOffset>(type: "timestamp with time zone", nullable: true),
+                    UserAgent = table.Column<string>(type: "text", nullable: true),
+                    CreatedAt = table.Column<DateTimeOffset>(type: "timestamp with time zone", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Feedback", x => x.Id);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Feedback_CreatedAt",
+                table: "Feedback",
+                column: "CreatedAt");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "Feedback");
+        }
+    }
+}

GerbilManagerWebAPI/Migrations/ApplicationContextModelSnapshot.cs

@@ -793,6 +793,48 @@ namespace GerbilManagerWebAPI.Migrations
                     b.ToTable("EnclosurePhotos");
                 });
 
+            modelBuilder.Entity("GerbilManagerWebAPI.Models.Feedback", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uuid");
+
+                    b.Property<DateTimeOffset?>("ClientTimestamp")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("Context")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<DateTimeOffset>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("EntityName")
+                        .HasColumnType("text");
+
+                    b.Property<Guid?>("GerbilId")
+                        .HasColumnType("uuid");
+
+                    b.Property<Guid?>("LitterId")
+                        .HasColumnType("uuid");
+
+                    b.Property<string>("Message")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<string>("Url")
+                        .HasColumnType("text");
+
+                    b.Property<string>("UserAgent")
+                        .HasColumnType("text");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CreatedAt");
+
+                    b.ToTable("Feedback");
+                });
+
             modelBuilder.Entity("GerbilManagerWebAPI.Models.Gerbil", b =>
                 {
                     b.Property<Guid>("Id")