feat: add server-level MCP auto-approval for wildcard tool servers

MCP servers configured with empty tools arrays (wildcard) now appear in the
auto-approval pill with a server-level toggle. When toggled, a server-level
approval key (mcp_server:<name>) is added to autoApprovedToolNames. The
sidecar matches this key against PermissionRequestMcp.ServerName to auto-
approve all tools from that server without needing individual tool names.

- Add buildMcpServerApprovalKey/isMcpServerApprovalKey helpers
- Create approval groups for all MCP servers including empty-tools ones
- Add serverApprovalKey to ApprovalToolGroup for server-level toggles
- Update sidecar RequiresToolCallApproval to check server-level keys
- Include server-level keys in listApprovalToolNames for pruning safety
- Add tests for both shared domain and sidecar approval matching

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

sidecar/tests/Aryx.AgentHost.Tests/CopilotWorkflowRunnerTests.cs

@@ -843,6 +843,36 @@ public sealed class CopilotWorkflowRunnerTests
         Assert.True(CopilotApprovalCoordinator.RequiresToolCallApproval(policy, "agent-1", "git.status"));
     }
 
+    [Fact]
+    public void RequiresToolCallApproval_HonorsMcpServerLevelApprovalKey()
+    {
+        ApprovalPolicyDto policy = new()
+        {
+            Rules =
+            [
+                new ApprovalCheckpointRuleDto
+                {
+                    Kind = "tool-call",
+                },
+            ],
+            AutoApprovedToolNames = ["mcp_server:Git MCP"],
+        };
+
+        // Server-level key approves any tool from that server
+        Assert.False(CopilotApprovalCoordinator.RequiresToolCallApproval(
+            policy, "agent-1", "git.status", null, "mcp_server:Git MCP"));
+        Assert.False(CopilotApprovalCoordinator.RequiresToolCallApproval(
+            policy, "agent-1", "git.diff", null, "mcp_server:Git MCP"));
+
+        // Different server still requires approval
+        Assert.True(CopilotApprovalCoordinator.RequiresToolCallApproval(
+            policy, "agent-1", "fs.read", null, "mcp_server:Filesystem"));
+
+        // Non-MCP tools unaffected
+        Assert.True(CopilotApprovalCoordinator.RequiresToolCallApproval(
+            policy, "agent-1", "unknown_tool"));
+    }
+
     [Fact]
     public void TryGetApprovalToolName_ResolvesDirectNamesAndRuntimeFallbacks()
     {