feat(policy): map --yolo to allowedTools wildcard policy

This PR maps the `--yolo` flag natively into a wildcard policy array
(`allowedTools: ["*"]`) and removes the concept of `ApprovalMode.YOLO` as a
distinct state in the application, fulfilling issue #11303.

This removes the hardcoded `ApprovalMode.YOLO` state and its associated
UI/bypasses. The `PolicyEngine` now evaluates YOLO purely via data-driven rules.

- Removes `ApprovalMode.YOLO`
- Removes UI toggle (`Ctrl+Y`) and indicators for YOLO
- Removes `yolo.toml`
- Updates A2A server and CLI config logic to translate YOLO into a wildcard tool
- Rewrites policy engine tests to evaluate the wildcard
- Enforces enterprise `disableYoloMode` and `secureModeEnabled` controls
  by actively preventing manual `--allowed-tools=*` bypasses.

Fixes #11303

docs/tools/planning.md

@@ -11,7 +11,8 @@ by the agent when you ask it to "start a plan" using natural language. In this
 mode, the agent is restricted to read-only tools to allow for safe exploration
 and planning.
 
-> **Note:** This tool is not available when the CLI is in YOLO mode.
+> **Note:** This tool is disabled when all tools are auto-approved via `--yolo`
+> or wildcard policies.
 
 - **Tool name:** `enter_plan_mode`
 - **Display name:** Enter Plan Mode