feat(cli-tools): add Devin CLI provider with ACP stdio executor

Wire Devin CLI as a routed provider that spawns the local `devin acp`
binary. Add the DevinCliExecutor, register it in the executor map, expose
its status through the cli-tools batch endpoint and devin-settings route,
and document setup in cliTools constants.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/shared/constants/cliTools.js

@@ -390,6 +390,32 @@ amp --model "{{model}}"
       },
     ],
   },
+  devin: {
+    id: "devin",
+    name: "Devin CLI",
+    image: "/providers/devin-cli.png",
+    color: "#6366F1",
+    description: "Cognition Devin CLI — local binary called by the Devin CLI provider via ACP/stdio",
+    configType: "guide",
+    installUrl: "https://cli.devin.ai",
+    notes: [
+      { type: "info", text: "This is a local dependency, not a routed CLI. The Devin CLI provider spawns `devin acp --agent-type summarizer` and relays its output." },
+      { type: "warning", text: "Install the Devin CLI and run `devin auth login` — without it, the provider returns a spawn error on first request." },
+    ],
+    guideSteps: [
+      { step: 1, title: "Install Devin CLI", desc: "Install via the official installer at cli.devin.ai.", docsUrl: "https://cli.devin.ai" },
+      { step: 2, title: "Authenticate", desc: "Log in once so the binary stores its own credentials." },
+      { step: 3, title: "Use the provider", desc: "Pick any Devin CLI model under the Providers tab — no API key field needed." },
+    ],
+    codeBlock: {
+      language: "bash",
+      code: `# Install Devin CLI (see https://cli.devin.ai for options)
+devin auth login
+
+# Verify detection (optional)
+devin --version`,
+    },
+  },
   // HIDDEN: gemini-cli
   // "gemini-cli": {
   //   id: "gemini-cli",