Add AWS Bedrock three-tier gateway routing (LiteLLM via Colin)

Routes AI tools across three tiers based on task complexity:
- Azure GPT-4o-mini always: redact, translate, timeline-basic, search-legal (mechanical tasks)
- Claude Haiku 4.5 (Bedrock): ask, summarize, timeline-deep, citations (Norwegian nuance)
- Claude Sonnet 4.6 (Bedrock): korrespond, legal-analysis, deep-research, barnevernet-analyze,
  discrepancy-find, advocate (public-facing legal output)

No AWS credentials in app — credentials live in LiteLLM on Colin (same as nova-lite).
Rollback: DBN_BEDROCK_ENABLED=false in .env, no code push needed.

Includes extended thinking support for Pro deep-research via chatWithThinking().
Claude Opus 4.7 constant added for future premium tier (needs litellm_config.yaml entry).

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

includes/LegalAnalysisAgent.php

@@ -3,6 +3,7 @@ declare(strict_types=1);
 
 require_once __DIR__ . '/bootstrap.php';
 require_once __DIR__ . '/AzureOpenAiGateway.php';
+require_once __DIR__ . '/DbnGatewayFactory.php';
 require_once __DIR__ . '/LegalTools.php';
 
 /**
@@ -22,12 +23,15 @@ final class DbnLegalAnalysisAgent
     private const LEGAL_TIMEOUT     = 60;
     private const LEGAL_MODEL       = 'dbn-legal-agent-v3';
 
-    private DbnAzureOpenAiGateway $azureMini;
+    private DbnAzureOpenAiGateway|DbnBedrockGateway $azureMini;
     private DbnLegalToolsService  $legalSvc;
 
     public function __construct()
     {
-        $this->azureMini = (new DbnAzureOpenAiGateway())->withDeployment('gpt-4o-mini');
+        // On Azure: gpt-4o-mini for extraction/synthesis. On Bedrock: factory picks Haiku/Sonnet.
+        $this->azureMini = DbnGatewayFactory::bedrockEnabled()
+            ? DbnGatewayFactory::makeForTool('legal-analysis')
+            : (new DbnAzureOpenAiGateway())->withDeployment('gpt-4o-mini');
         $this->legalSvc  = new DbnLegalToolsService();
     }