Add debug copy button and functionality

Includes a button for administrators to copy all transcripts and the
document markdown to the clipboard.
The data is embedded as JSON in a script tag and pre-sanitized to
prevent
`</script>` tag injection.
The JavaScript handles copying to the clipboard using the modern
Clipboard API,
with a fallback for older browsers.

server/templates/case_page.html

@@ -400,6 +400,15 @@
                 <input type="hidden" name="return_to" value="/web/cases/{{ case_id }}">
                 <button type="submit">Reset</button>
             </form>
+            <button
+                type="button"
+                id="debug-copy-btn"
+                class="admin-only"
+                title="Alle Transkripte + Dokument-Markdown in die Zwischenablage"
+            >Debug-Copy</button>
+            <script type="application/json" id="debug-copy-data">
+{{ debug_copy_json|safe }}
+            </script>
             {% endif %}
         </div>
 
@@ -604,5 +613,48 @@
         <script>
 {% include "partials/oneliner_edit.js" %}
         </script>
+        {% if is_admin %}
+        <script>
+            (() => {
+                const btn = document.getElementById("debug-copy-btn");
+                const data = document.getElementById("debug-copy-data");
+                if (!btn || !data) return;
+                let payload;
+                try {
+                    payload = JSON.parse(data.textContent);
+                } catch (_) {
+                    return;
+                }
+                btn.addEventListener("click", async () => {
+                    const parts = [...(payload.transcripts || [])];
+                    if (payload.document) parts.push(payload.document);
+                    const text = parts.join("\n\n---\n\n");
+                    let ok = false;
+                    try {
+                        if (navigator.clipboard && window.isSecureContext) {
+                            await navigator.clipboard.writeText(text);
+                            ok = true;
+                        }
+                    } catch (_) {}
+                    if (!ok) {
+                        const ta = document.createElement("textarea");
+                        ta.value = text;
+                        ta.setAttribute("readonly", "");
+                        ta.style.position = "fixed";
+                        ta.style.top = "-1000px";
+                        document.body.appendChild(ta);
+                        ta.select();
+                        try { ok = document.execCommand("copy"); } catch (_) {}
+                        ta.remove();
+                    }
+                    if (ok) {
+                        const original = btn.textContent;
+                        btn.textContent = "Kopiert!";
+                        setTimeout(() => { btn.textContent = original; }, 1500);
+                    }
+                });
+            })();
+        </script>
+        {% endif %}
     </body>
 </html>