Sanitize codebase, reorganize docs, and add missing deploy files

Remove dead code identified in docs/SANITIZATION-REVIEW.md:
- app/blueprints/content_old.py and app/blueprints/playlist.py
- app/models/group.py, app/utils/nginx_config_reader.py
- orphaned templates (content_list, edit_content, upload_content,
  player_page) and the related group/Template references

Result: 6 blueprints, 82 routes, no dead modules or orphan templates.

Add files that deploy.sh and docker-entrypoint.sh already require but
which were never tracked:
- https_manager.py       (referenced by deploy.sh, migrate_network.sh,
                          docker-entrypoint.sh)
- Caddyfile.example      (seeded by deploy.sh; its absence aborts deploy)

Relocate generated Graphify artifacts from graphify-out/ to
docs/graphify-out/ (110 files, no content change) and archive the
superseded docs under docs/.

Ignore hygiene:
- ignore ad-hoc .env backups (.env.bak*) — they contain live secrets
- keep the pre-sanitization snapshots (docs/legacy code/,
  docs/old_code_documentation/) on disk but out of the repo

Fix .env.example: drop a duplicated config block, genericize the
hardcoded host IP, and document HOSTNAME_INTERNAL.

app/templates/admin/build_player.html

@@ -42,6 +42,24 @@
         {% endif %}
     </div>
 
+    <!-- Live build progress (updated by polling below) -->
+    <div class="card" id="build-progress" style="display: none;">
+        <h2>Build progress</h2>
+        <p id="build-progress-text" style="margin: 0;">
+            <span class="badge badge-warning" id="build-progress-badge">⏳ Running</span>
+            <span id="build-progress-step"></span>
+        </p>
+        <p id="build-progress-message" style="color: #6c757d; margin-top: 8px;"></p>
+        <div style="margin-top: 10px;">
+            <button type="button" class="btn btn-secondary" onclick="window.location.reload()">
+                🔄 Refresh page
+            </button>
+        </div>
+        <p style="color: #6c757d; font-size: 13px; margin-top: 10px;">
+            The clone takes a couple of minutes. You can leave this page and come back.
+        </p>
+    </div>
+
     <form method="POST" action="{{ url_for('admin.build_player_action') }}">
         <!-- Repository -->
         <div class="card">
@@ -114,10 +132,12 @@
         <div class="card">
             <h2>3. Build</h2>
             <div class="card-actions" style="display: flex; gap: 10px; flex-wrap: wrap;">
-                <button type="submit" name="action" value="build_and_config" class="btn btn-primary">
+                <button type="submit" name="action" value="build_and_config"
+                        class="btn btn-primary" id="btn-build-all">
                     ⬇️ Build files &amp; write config
                 </button>
-                <button type="submit" name="action" value="build_files" class="btn btn-secondary">
+                <button type="submit" name="action" value="build_files"
+                        class="btn btn-secondary" id="btn-build-files">
                     Build files only
                 </button>
                 <button type="submit" name="action" value="save_config" class="btn btn-secondary">
@@ -127,4 +147,64 @@
         </div>
     </form>
 </div>
+
+<script>
+// Poll the build status so the admin sees live progress instead of a request
+// that appears to hang (the clone takes ~1-2 minutes).
+(function () {
+    const statusUrl = "{{ url_for('admin.build_player_status') }}";
+    const panel   = document.getElementById('build-progress');
+    const badge   = document.getElementById('build-progress-badge');
+    const step    = document.getElementById('build-progress-step');
+    const message = document.getElementById('build-progress-message');
+    const bAll    = document.getElementById('btn-build-all');
+    const bFiles  = document.getElementById('btn-build-files');
+    let sawRunning = false;
+
+    function render(s) {
+        const state = s.state || 'idle';
+
+        if (state === 'running') {
+            sawRunning = true;
+            panel.style.display = 'block';
+            badge.className = 'badge badge-warning';
+            badge.textContent = '⏳ Running';
+            step.textContent = s.step || '';
+            message.textContent = '';
+            if (bAll)   { bAll.disabled = true;   bAll.textContent   = '⏳ Building…'; }
+            if (bFiles) { bFiles.disabled = true; }
+            return;
+        }
+
+        // Reached a terminal state.
+        if (state === 'success' || state === 'error') {
+            panel.style.display = 'block';
+            if (state === 'success') {
+                badge.className = 'badge badge-success';
+                badge.textContent = '✅ Build complete';
+            } else {
+                badge.className = 'badge badge-danger';
+                badge.textContent = '❌ Build failed';
+            }
+            step.textContent = '';
+            message.textContent = s.message || '';
+            if (sawRunning) {
+                // Reload once so the staged-version panel reflects the new build.
+                setTimeout(function () { window.location.reload(); }, 1500);
+            }
+        }
+    }
+
+    function poll() {
+        fetch(statusUrl, { headers: { 'Accept': 'application/json' }, cache: 'no-store' })
+            .then(function (r) { return r.ok ? r.json() : null; })
+            .then(function (s) { if (s) render(s); })
+            .catch(function () { /* transient — keep polling */ });
+    }
+
+    poll();
+    setInterval(poll, 3000);
+})();
+</script>
 {% endblock %}
+