feat: add Jarvis agent verification foundation

Add Day 1 agent runtime foundations with task and event schemas, verifier support, capability metadata, graph event tracing, and regression coverage while preserving the direct execution path.

backend/app/agents/schemas/task.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from typing import Any, Literal
+
+from pydantic import BaseModel, Field
+
+
+TaskLifecycleStatus = Literal["pending", "in_progress", "completed", "failed", "blocked"]
+VerificationStatus = Literal["passed", "failed", "skipped"]
+
+
+class AgentTask(BaseModel):
+    task_id: str
+    title: str
+    status: TaskLifecycleStatus = "pending"
+    owner_agent_id: str | None = None
+    role: str | None = None
+    goal: str | None = None
+    expected_evidence: list[dict[str, Any]] = Field(default_factory=list)
+    evidence: list[dict[str, Any]] = Field(default_factory=list)
+    result_summary: str | None = None
+    created_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
+    updated_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
+
+
+class TaskResult(BaseModel):
+    task_id: str
+    status: VerificationStatus
+    summary: str | None = None
+    evidence: list[dict[str, Any]] = Field(default_factory=list)
+    output_data: dict[str, Any] | None = None