sync: Agent Architecture Overhaul - AI SDK 6 + workflow optimization

Synced from private repo (feature/ai-sdk-6-upgrade):
- Upgrade AI SDK 5 → 6 (packages + API changes)
- Add sqliteQuery tool for flexible read-only queries
- New WorkflowExecutor with workflow-specific tools
- 83% token reduction for workflow execution
- Remove mini-rah dead code (simplified architecture)
- Add context management usage endpoint
- Fix Connect workflow instructions
- Clickable node references in workflow UI

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/rah/chat/route.ts

@@ -1,5 +1,5 @@
 import { NextRequest } from 'next/server';
-import { streamText, convertToCoreMessages } from 'ai';
+import { streamText, convertToModelMessages } from 'ai';
 import { createAnthropic } from '@ai-sdk/anthropic';
 import { createOpenAI } from '@ai-sdk/openai';
 import { getHelperTools, getDefaultToolNamesForRole } from '@/tools/infrastructure/registry';
@@ -265,7 +265,7 @@ export async function POST(request: NextRequest) {
       } : {})
     }));
 
-    const coreMessages = convertToCoreMessages(sanitizedMessages);
+    const coreMessages = await convertToModelMessages(sanitizedMessages);
     const allMessages = [...systemMessages, ...coreMessages];
     
     // Debug logging (can be removed in production)

app/api/rah/usage/route.ts

@@ -0,0 +1,28 @@
+import { NextRequest } from 'next/server';
+import { getSQLiteClient } from '@/services/database/sqlite-client';
+
+export async function GET(request: NextRequest) {
+  const sessionId = request.nextUrl.searchParams.get('sessionId');
+
+  if (!sessionId) {
+    return Response.json({ inputTokens: 0 });
+  }
+
+  try {
+    const sqlite = getSQLiteClient();
+    const row = sqlite.prepare(`
+      SELECT json_extract(metadata, '$.input_tokens') as input_tokens
+      FROM chats
+      WHERE thread_id LIKE ?
+      ORDER BY created_at DESC
+      LIMIT 1
+    `).get(`%${sessionId}%`) as { input_tokens: number | null } | undefined;
+
+    return Response.json({
+      inputTokens: row?.input_tokens ?? 0
+    });
+  } catch (error) {
+    console.error('Usage fetch error:', error);
+    return Response.json({ inputTokens: 0 });
+  }
+}

app/api/workflows/execute/route.ts

@@ -2,7 +2,7 @@ import { NextRequest, NextResponse } from 'next/server';
 import { WorkflowRegistry } from '@/services/workflows/registry';
 import { getSQLiteClient } from '@/services/database/sqlite-client';
 import { AgentDelegationService } from '@/services/agents/delegation';
-import { WiseRAHExecutor } from '@/services/agents/wiseRAHExecutor';
+import { WorkflowExecutor } from '@/services/agents/workflowExecutor';
 import { getAutoContextSummaries } from '@/services/context/autoContext';
 
 export async function POST(request: NextRequest) {
@@ -112,12 +112,12 @@ ${nodeId ? `Target Node ID: ${nodeId}` : 'No specific node targeted (general wor
       task,
       context: contextLines,
       expectedOutcome: workflow.expectedOutcome,
-      agentType: 'wise-rah',
+      agentType: 'workflow',
       supabaseToken: null,
     });
 
     // Fire-and-forget execution
-    void WiseRAHExecutor.execute({
+    void WorkflowExecutor.execute({
       sessionId: delegation.sessionId,
       task,
       context: contextLines,