r006: Add unraid_system_shell tool (direct terminal access)

- New helper runShell(): executes /bin/sh -c, returns {exit_code, stdout, stderr} as JSON
- New tool unraid_system_shell: direct shell access on Unraid host (root)
  - params: command (required), timeout_seconds (1-300, default 60)
  - output size-limited via sanitizeLogOutput
- Version bump r005 -> r006

src/tools.ts

@@ -1,9 +1,9 @@
 /**
  * MUA — Mikes Unraid Agent
- * tools.ts — MCP Tool-Definitionen (21 Tools)
+ * tools.ts — MCP Tool-Definitionen (22 Tools)
  *
  * Portiert von mcp/tools.php. Schema: unraid_<kategorie>_<aktion>
- * Kategorien: docker (14), network (6), system (1).
+ * Kategorien: docker (14), network (6), system (2).
  */
 
 import {
@@ -19,6 +19,7 @@ import {
   probeDualstack,
   connectionTest,
   validateName,
+  runShell,
 } from "./helpers";
 
 export interface ToolDef {
@@ -294,7 +295,7 @@ export const TOOLS: ToolDef[] = [
     },
   },
 
-  // ── System (1) ────────────────────────────────────────────────────────
+  // ── System (2) ────────────────────────────────────────────────────────
   {
     name: "unraid_system_connection_test",
     description:
@@ -302,6 +303,30 @@ export const TOOLS: ToolDef[] = [
     inputSchema: empty,
     handler: () => connectionTest(),
   },
+  {
+    name: "unraid_system_shell",
+    description:
+      "Execute a shell command on the Unraid host (as root, via /bin/sh -c) and return exit code, stdout, and stderr. Use for direct terminal access: file inspection, system commands, package info, log reading, etc. Commands run with a timeout and output is size-limited.",
+    inputSchema: {
+      type: "object",
+      properties: {
+        command: str(
+          "Shell command to execute on the Unraid host (run via /bin/sh -c)",
+        ),
+        timeout_seconds: int("Timeout in seconds (1-300, default 60)"),
+      },
+      required: ["command"],
+    },
+    handler: (a) => {
+      const command = (a["command"] as string) ?? "";
+      if (command.trim() === "") throw new Error("command is required");
+      const timeout = Number(a["timeout_seconds"] ?? 60);
+      if (timeout < 1 || timeout > 300) {
+        throw new Error("timeout_seconds must be between 1 and 300");
+      }
+      return runShell(command, timeout);
+    },
+  },
 ];
 
 export function toolByName(name: string): ToolDef | undefined {