feat(tools): add letter length + summary depth controls; harden korrespond §-discipline

- Summarize: new depth param (brief/standard/detailed) with depth-aware prompt
  instructions and coverage mandate; wired through API + JS
- Korrespond: new letter length param (concise/standard/detailed) injected as
  Lengde: instruction in draft pass; wired through API + JS
- Korrespond draft prompt: add §-discipline rule (cite only directly relevant §§)
  plus Opphevet guard (aligned with dobetterlegal-tools)

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

api/korrespond.php

@@ -171,6 +171,8 @@ try {
     if (in_array($inputEngine, ['azure_mini', 'claude_sonnet'], true)) {
         $engine = $inputEngine;
     }
+    $length = in_array($input['length'] ?? '', ['concise', 'standard', 'detailed'], true)
+        ? (string)$input['length'] : 'standard';
     $ftRemaining = dbnToolsFreeTierDeduct($ftUid, 'korrespond');
     $creditDeducted = true;
 
@@ -179,7 +181,7 @@ try {
         : null;
 
     // ── Pass 2: retrieve law → draft → self-check → translate ──────────────────
-    $result = $agent->generate($intake, $classify, $emit, $engine, $personaSlug);
+    $result = $agent->generate($intake, $classify, $emit, $engine, $personaSlug, $length);
     $result['ok']         = true;
     $result['latency_ms'] = (int)round((microtime(true) - $startTime) * 1000);
     if ($ftRemaining >= 0) {