feat(settings): add AI Router profiles and attach one per lane

A new **AI Router** tab in Settings, next to Codex, stores named router
endpoints (9Router, OpenRouter, a self-hosted gateway) as profiles: a base
URL, an API key, a default model and an optional per-tier override. The tab
only stores them; a lane CHOOSES one in the Add-lane modal, via a Native /
AI Router radio, and that choice is written into the lane's own config.

The two CLIs are configured differently, and the difference is theirs:

  - a claude lane gets eight `env` keys merged into its own
    `.claude/settings.local.json` (`.local` because the value holds a key);
  - a codex lane gets `$CODEX_HOME/<name>.config.toml` — the layer
    `codex -p <name>` loads — because Codex has NO project-level config.
    Its base `config.toml` is never touched.

Native is a built-in profile rather than a code branch, so "go back to
native" is the same write path. It blanks the two connection variables
instead of removing them (an absent key at project scope lets a USER-level
router apply) and removes the model names instead of writing them (writing
them would override the user's own global model choice).

Key material never leaves the server: profiles live one file each under
`<CLAUDE_HOME>/agenthub-routers/` (0700/0600), `GET /api/ai-routers`
reports only `hasKey`, and there is deliberately no route returning one
profile in full.

Three things this had to get right, each found by review and verified
against the real tools rather than assumed:

  - `wire_api = "chat"` is rejected outright by codex-cli 0.149 ("no longer
    supported"), so every codex lane on a router would have failed to start.
    The layer writes "responses", and writes `env_key` only when the profile
    actually has a key — naming an unset variable is itself a startup error.
  - The key must never be TYPED into a pane. `tmux.sendCommand` used
    `send-keys` with a `KEY='…' cmd` prefix, which the dashboard streams to
    every attached browser and bash appends to history; it now takes over the
    idle pane with `respawn-pane -k -e`, passing env through argv the way
    `newSession` always has. Verified on tmux 3.4: multi-element argv arrives
    intact and the pane renders no trace of the value.
  - Attaching COPIES a profile, so editing or deleting one in Settings has to
    reach the lanes already using it. An edit re-applies it (a rotated key
    would otherwise never reach the lane still holding the revoked one); a
    delete resets those lanes to native and removes the Codex layer file.
    Both report per-lane failures, which the tab surfaces.

`.claude/settings.local.json` is added to the lane's git exclude, for both
native and router lanes: `agenthub lanes reset` runs `git clean -fd` without
`-x`, so an un-excluded settings file is deleted on reset — and untracked
meant the key was committable.

DB: `lanes.router_profile`, nullable, additive. Written only by
`setRouterProfile` beside the disk write, never through `PATCHABLE`.

server/__tests__/pty-run.test.js

@@ -94,7 +94,7 @@ describe("pty-run", () => {
     assert.ok(!calls.some((c) => c[0] === "send-keys"), "must not type over a live agent");
   });
 
-  it("spawnRun types the argv into an existing session idling at a shell prompt", () => {
+  it("spawnRun runs the argv in an existing session idling at a shell prompt", () => {
     const calls = [];
     tmux.__setExecImpl((args) => {
       calls.push(args);
@@ -103,24 +103,24 @@ describe("pty-run", () => {
     });
     pty.spawnRun({ laneId: 8, cwd: "/tmp/repo", resumeSessionId: "abc12345" });
     assert.ok(!calls.some((c) => c[0] === "new-session"), "must not create a duplicate session");
-    const literal = calls.find((c) => c[0] === "send-keys" && c[3] === "-l");
-    assert.ok(literal, "expected a literal send-keys with the command line");
-    assert.match(literal[4], /^AGENTHUB_LANE_ID='8' 'claude' .*'--resume' 'abc12345'$/);
-    assert.ok(
-      calls.some((c) => c[0] === "send-keys" && c[3] === "Enter"),
-      "expected the command to be submitted"
-    );
+    const respawn = calls.find((c) => c[0] === "respawn-pane");
+    assert.ok(respawn, "expected the idle shell to be replaced by the argv");
+    const argv = respawn.slice(respawn.indexOf("--") + 1);
+    assert.equal(argv[0], "claude");
+    assert.deepEqual(argv.slice(-2), ["--resume", "abc12345"]);
   });
 
-  it("spawnRun single-quotes an initial prompt typed into an existing shell pane", () => {
-    let literal = null;
+  it("spawnRun passes an initial prompt as one argv element, never a shell line", () => {
+    // No shell is involved any more, so a prompt full of shell metacharacters
+    // is just a string — but it must still arrive whole and unmangled.
+    let respawn = null;
     tmux.__setExecImpl((args) => {
       if (args[0] === "display-message") return "zsh\n";
-      if (args[0] === "send-keys" && args[3] === "-l") literal = args[4];
+      if (args[0] === "respawn-pane") respawn = args;
       return "";
     });
     pty.spawnRun({ laneId: 9, cwd: "/tmp/repo", initialPrompt: "don't; rm -rf /" });
-    assert.ok(literal.endsWith(`'don'\\''t; rm -rf /'`), literal);
+    assert.equal(respawn.at(-1), "don't; rm -rf /");
   });
 
   it("spawnRun puts AGENTHUB_LANE_ID in the new session's environment", () => {
@@ -142,17 +142,22 @@ describe("pty-run", () => {
     assert.ok(at < newSessionArgv.indexOf("--"));
   });
 
-  it("spawnRun prefixes AGENTHUB_LANE_ID when typing into an existing shell pane", () => {
-    let literal = null;
+  it("spawnRun passes AGENTHUB_LANE_ID through tmux -e when reusing a shell pane", () => {
+    let respawn = null;
     tmux.__setExecImpl((args) => {
       if (args[0] === "display-message") return "bash\n";
-      if (args[0] === "send-keys" && args[3] === "-l") literal = args[4];
+      if (args[0] === "respawn-pane") respawn = args;
       return "";
     });
     pty.spawnRun({ laneId: 12, cwd: "/tmp/repo", tool: "codex" });
-    // An assignment prefix on the same line: tmux's -e only applies at session
-    // creation, and a live shell takes its env from the command line.
-    assert.match(literal, /^AGENTHUB_LANE_ID='12' 'codex'/);
+    // Through argv, never as a shell assignment typed into the pane: this is
+    // also the path an AI Router's API key takes, and a typed line would be
+    // rendered to every attached browser and land in the shell history.
+    const at = respawn.indexOf("-e");
+    assert.ok(at > -1, "expected a tmux -e environment flag");
+    assert.equal(respawn[at + 1], "AGENTHUB_LANE_ID=12");
+    assert.ok(at < respawn.indexOf("--"));
+    assert.equal(respawn.at(-1), "codex");
   });
 
   it("spawnRun with resumeSessionId passes --resume in argv", () => {