feat(timeline): add live filter, actor chips, group headers, copy button, source toggle, count badge

- Live search/filter bar: filters events by keyword across event, actor, source_excerpt, date
- Actor filter chips: click to filter by actor, multi-select, teal active state
- Year/month group headers when sorted chronologically (── 2023 ──, Mar 2024 ──)
- Per-event copy button (hover-revealed 📋): copies "date · actor · event" to clipboard
- "Hide/show sources" toggle: collapses all source excerpts without re-rendering
- Count badge: "23 events · 3 actors · 2022–2025" above the list
- applyTimelineFilters() unifies sort + actor + text filters in one re-render pass
- CSV export now includes end_date column
- Reset all filter state on each new run

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

api/deep-research.php

@@ -65,8 +65,9 @@ try {
     if (mb_strlen($advocateRole, 'UTF-8') > 200) {
         throw new DbnToolsHttpException('advocate_role is too long.', 422, 'advocate_role_too_long');
     }
-    $priorContext = is_array($input['prior_context'] ?? null) ? $input['prior_context'] : null;
-    $branchNotes  = mb_substr(trim((string)($input['branch_notes'] ?? '')), 0, 1000, 'UTF-8');
+    $priorContext        = is_array($input['prior_context'] ?? null) ? $input['prior_context'] : null;
+    $branchNotes        = mb_substr(trim((string)($input['branch_notes'] ?? '')), 0, 1000, 'UTF-8');
+    $subQsOverride      = is_array($input['sub_questions_override'] ?? null) ? $input['sub_questions_override'] : [];
 
     if (mb_strlen($seedQuery, 'UTF-8') > 4000) {
         throw new DbnToolsHttpException('Query is too long.', 422, 'query_too_long');
@@ -125,7 +126,8 @@ try {
         $emit,
         $advocateRole,
         $priorContext,
-        $branchNotes
+        $branchNotes,
+        $subQsOverride
     );
 
     $result['ok'] = true;

api/generate-subq.php

@@ -0,0 +1,56 @@
+<?php
+declare(strict_types=1);
+
+require_once __DIR__ . '/../includes/bootstrap.php';
+require_once __DIR__ . '/../includes/DeepResearchAgent.php';
+
+dbnToolsRequireMethod('POST');
+dbnToolsRequireAuth();
+
+header('Content-Type: application/json; charset=utf-8');
+header('Cache-Control: no-store');
+
+try {
+    $raw = file_get_contents('php://input');
+    if ($raw === false || strlen($raw) > 20000) {
+        throw new DbnToolsHttpException('Request body unreadable or too large.', 413, 'body_too_large');
+    }
+    $input = json_decode((string)$raw, true);
+    if (!is_array($input)) {
+        throw new DbnToolsHttpException('Request body must be valid JSON.', 400, 'invalid_json');
+    }
+
+    $seedQuery    = mb_substr(trim((string)($input['query'] ?? '')), 0, 4000, 'UTF-8');
+    $pastedText   = mb_substr(trim((string)($input['paste_text'] ?? '')), 0, 64000, 'UTF-8');
+    $engine       = (string)($input['engine'] ?? 'azure_mini');
+    $language     = dbnToolsNormalizeLanguage($input['language'] ?? 'en');
+    $controls     = is_array($input['controls'] ?? null) ? $input['controls'] : [];
+    $advocateRole = mb_substr(trim((string)($input['advocate_role'] ?? '')), 0, 200, 'UTF-8');
+    $priorContext = is_array($input['prior_context'] ?? null) ? $input['prior_context'] : null;
+    $branchNotes  = mb_substr(trim((string)($input['branch_notes'] ?? '')), 0, 1000, 'UTF-8');
+
+    if ($seedQuery === '' && $pastedText === '') {
+        throw new DbnToolsHttpException('Provide a query or pasted text.', 422, 'missing_seed');
+    }
+
+    $result = (new DbnDeepResearchAgent())->generateSubQPreview(
+        $seedQuery,
+        $pastedText,
+        $engine,
+        $language,
+        $controls,
+        $advocateRole,
+        $priorContext,
+        $branchNotes
+    );
+
+    echo json_encode($result, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
+
+} catch (DbnToolsHttpException $e) {
+    http_response_code($e->getCode() ?: 500);
+    echo json_encode(['ok' => false, 'code' => $e->getSlug(), 'message' => $e->getMessage()]);
+} catch (Throwable $e) {
+    error_log('DBN generate-subq error: ' . $e->getMessage());
+    http_response_code(500);
+    echo json_encode(['ok' => false, 'code' => 'internal_error', 'message' => 'Could not generate sub-questions.']);
+}