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>

summarize.php

@@ -24,6 +24,14 @@ require_once __DIR__ . '/includes/layout.php';
                     </div>
                     <p class="upload-hint">Azure engines use your BNL Azure credits. GPU runs the local LiteLLM proxy on the GPU server.</p>
 
+                    <div class="control-row" id="sumDepthControl">
+                        <span class="control-label">Summary depth</span>
+                        <label><input type="radio" name="sumDepth" value="brief"> Brief</label>
+                        <label><input type="radio" name="sumDepth" value="standard" checked> Standard &#9733;</label>
+                        <label><input type="radio" name="sumDepth" value="detailed"> Detailed</label>
+                    </div>
+                    <p class="upload-hint">Brief: 1-2 sentence executive summary. Standard: balanced summary with all key facts. Detailed: comprehensive &#8212; covers every fact, party, date, and legal reference.</p>
+
                     <details class="advanced-panel" id="sumSlicesPanel">
                         <summary class="advanced-toggle">Legal corpus enrichment <small class="control-hint">(optional)</small></summary>
                         <p class="upload-hint">When one or more slices are enabled, the tool searches the Do Better Norge legal corpus for relevant passages and prepends them to the prompt. All slices are off by default — enable only what applies to your document.</p>