feat(tools): persona selector across standalone tools + dashboard chat

Wire the legal-domain persona picker into corpus, deep-research, korrespond and
the dashboard chat. Each endpoint reads the chosen profile, resolves its packages
against client 57, and scopes retrieval via package_ids (falling back to family
when omitted). New dashboard tenants now subscribe to all DBN domain packages so
persona switching survives the subscription intersection.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

api/deep-research.php

@@ -70,6 +70,9 @@ try {
     $priorContext        = is_array($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'] : [];
+    $personaSlug        = (isset($input['profile']) && is_string($input['profile']) && trim($input['profile']) !== '')
+        ? trim($input['profile'])
+        : null;
 
     if (mb_strlen($seedQuery, 'UTF-8') > 4000) {
         throw new DbnToolsHttpException('Query is too long.', 422, 'query_too_long');
@@ -139,7 +142,8 @@ try {
         $advocateRole,
         $priorContext,
         $branchNotes,
-        $subQsOverride
+        $subQsOverride,
+        $personaSlug
     );
 
     $result['ok'] = true;