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/reference/policy-engine.md

@@ -157,9 +157,9 @@ For example:
 
 Approval modes allow the policy engine to apply different sets of rules based on
 the CLI's operational mode. A rule can be associated with one or more modes
-(e.g., `yolo`, `autoEdit`, `plan`). The rule will only be active if the CLI is
-running in one of its specified modes. If a rule has no modes specified, it is
-always active.
+(e.g., `autoEdit`, `plan`). The rule will only be active if the CLI is running
+in one of its specified modes. If a rule has no modes specified, it is always
+active.
 
 - `default`: The standard interactive mode where most write tools require
   confirmation.
@@ -167,7 +167,6 @@ always active.
   auto-approved.
 - `plan`: A strict, read-only mode for research and design. See
   [Customizing Plan Mode Policies](../cli/plan-mode.md#customizing-policies).
-- `yolo`: A mode where all tools are auto-approved (use with extreme caution).
 
 ## Rule matching
 
@@ -424,6 +423,5 @@ out-of-the-box experience.
   checked individually.
 - **Write tools** (like `write_file`, `run_shell_command`) default to
   **`ask_user`**.
-- In **`yolo`** mode, a high-priority rule allows all tools.
 - In **`autoEdit`** mode, rules allow certain write operations to happen without
   prompting.