chore: v2.8.15 — Oh My Pi login sharing, omp --allow-home, Markdown Preview default, first-login password

- omp-share.js: an admin's switch (S3) runs omp's own auth broker + gateway as
  the host on loopback; a member's omp pane reaches it as a scoped client keyed
  by its pane token (clients file = live omp panes only), runs on
  --model agenthub/<model>, never holds a credential.
- omp catalog: --allow-home, so a workspace at the account's home keeps its
  sessions there (they were recorded under a temp dir and dropped).
- Settings → Appearance → Open Markdown as: Preview (default) or Raw, for
  Files/Changes, the config viewer and a chat's file panel.
- First-login password change and password rules, avatar URLs, Artifacts
  "Mine" includes installed shared skills/plugins, a member's own hook pages.

bin/agenthub.js

@@ -4166,14 +4166,25 @@ async function cmdUsers(sub, positional, flags) {
     case "list":
       table(
         ["id", "username", "role", "state"],
-        auth.listUsers().map((u) => [u.id, u.username, u.role, u.disabled ? "disabled" : "active"])
+        auth
+          .listUsers()
+          .map((u) => [
+            u.id,
+            u.username,
+            u.role,
+            u.disabled ? "disabled" : u.mustChangePassword ? "active (new password due)" : "active",
+          ])
       );
       return;
     case "add": {
       need();
       const role = typeof flags.role === "string" ? flags.role : "developer";
-      const user = await auth.createUser(name, await newPassword(`Password for ${name}`), role);
-      console.log(`${c.green("✔")} ${user.username} added (${user.role})`);
+      const user = await auth.createUser(name, await newPassword(`Password for ${name}`), role, {
+        mustChange: true,
+      });
+      console.log(
+        `${c.green("✔")} ${user.username} added (${user.role}) — they choose their own password at first login`
+      );
       return;
     }
     case "passwd":