fix(filesystem): correct outputSchema for directory_tree and move_file

Why this change was needed:
Both tools declared outputSchema as { content: z.string() } but their
handlers return { content: [{ type: "text", text: "..." }] } - an array
of content blocks. This mismatch caused MCP validation error -32602.

What changed:
- Updated directory_tree outputSchema to declare content as array of
  text content blocks
- Updated move_file outputSchema with the same fix
- Schema now matches the actual return type of both handlers

Problem solved:
Clients using structured content validation no longer receive -32602
errors when calling directory_tree or move_file tools.

Fixes #3093, Fixes #3106

Author: cardmagic

src/filesystem/index.ts

@@ -518,7 +518,12 @@ server.registerTool(
       path: z.string(),
       excludePatterns: z.array(z.string()).optional().default([])
     },
-    outputSchema: { content: z.string() },
+    outputSchema: {
+      content: z.array(z.object({
+        type: z.literal("text"),
+        text: z.string()
+      }))
+    },
     annotations: { readOnlyHint: true }
   },
   async (args: z.infer<typeof DirectoryTreeArgsSchema>) => {
@@ -588,7 +593,12 @@ server.registerTool(
       source: z.string(),
       destination: z.string()
     },
-    outputSchema: { content: z.string() },
+    outputSchema: {
+      content: z.array(z.object({
+        type: z.literal("text"),
+        text: z.string()
+      }))
+    },
     annotations: { readOnlyHint: false, idempotentHint: false, destructiveHint: false }
   },
   async (args: z.infer<typeof MoveFileArgsSchema>) => {