feat(F): F-WORK agent_workstream + F-EMAIL/CONTACT/FOLLOW/REPORT prebuilt agents

- F-WORK: app/ai/agent_workstream.py (201 lines) — post_agent_message, post_agent_step, post_agent_result, post_approval_request
- F-EMAIL: prebuilt/email_triage_agent.py — E-Mail-Triage-Agent with 3 tools, max 10 steps, $0.50 budget
- F-CONTACT: prebuilt/contact_enrichment_agent.py — Contact-Enrichment-Agent with 3 tools, max 8 steps, $0.30 budget
- F-FOLLOW: prebuilt/follow_up_agent.py — Follow-up-Agent with 3 tools, max 8 steps, $0.30 budget
- F-REPORT: prebuilt/report_agent.py — Report-Agent with 2 tools, max 12 steps, $0.50 budget
- All compile checks pass

app/plugins/builtins/automation/prebuilt/email_triage_agent.py

@@ -0,0 +1,51 @@
+"""Pre-built E-Mail-Triage-Agent.
+
+Sorts and prioritizes incoming emails automatically.
+"""
+from __future__ import annotations
+import uuid
+from app.plugins.builtins.automation.models import AgentDefinition
+
+EMAIL_TRIAGE_SYSTEM_PROMPT = """You are an E-Mail Triage Agent for a CRM system.
+
+Your task is to sort and prioritize incoming emails for the user.
+
+For each email, you should:
+1. Classify it as: urgent, important, normal, low_priority, or spam
+2. Extract key information: sender, subject, intent, action items
+3. Suggest a response category: reply_needed, forward, archive, delete
+4. Identify any contacts that should be linked
+
+Use the available tools to:
+- Fetch emails for contacts (get_contact_mails)
+- Summarize email threads (summarize_mail_thread)
+- Call CRM API for contact/company data (call_crm_api)
+
+Output format:
+- Provide a structured summary of each email
+- Include priority level and suggested action
+- Be concise but thorough
+
+Do NOT send emails or make changes. You are advisory only.
+"""
+
+def create_email_triage_agent(
+    tenant_id: uuid.UUID, user_id: uuid.UUID
+) -> AgentDefinition:
+    return AgentDefinition(
+        tenant_id=tenant_id,
+        name="E-Mail-Triage-Agent",
+        description="Sortiert und priorisiert eingehende E-Mails automatisch",
+        system_prompt=EMAIL_TRIAGE_SYSTEM_PROMPT,
+        llm_model="openai/gpt-4o-mini",
+        tool_ids=["get_contact_mails", "summarize_mail_thread", "call_crm_api"],
+        max_steps=10,
+        max_duration_seconds=120,
+        budget_limit_usd=0.50,
+        mode="reactive",
+        is_active=True,
+        temperature=0.3,
+        max_tokens=2000,
+        trace_mode="standard",
+        created_by=user_id,
+    )