feat(dashboard): show Cockpit login credentials inline

Cockpit's PAM auth at https://localhost:9090/ rejects login when the
target user has no password set in /etc/shadow. podman-machine WSL
distros ship `user` (uid 1000) passwordless by default -- so the
operator hits "Authentication failed" with no obvious recovery path.

Dashboard's Self-replication-loop panel now prints the credentials
inline next to the Cockpit URL:

  ●  Cockpit     https://localhost:9090/   login: user / mios

`MIOS_LINUX_USER` falls back to "mios" if the env doesn't set it
(matches the same default used everywhere else in the dashboard).
`MIOS_DEV_DEFAULT_PASSWORD` defaults to "mios" so deployed-MiOS hosts
that set their own operator password just need to export it before
the dashboard renders.

Companion change in mios-bootstrap/build-mios.ps1 (separate commit):
Invoke-MiosQuadletOverlay now sets both `user` and `mios` to
"mios" via chpasswd at the same time it installs the sudoers drop-
in -- single-tenant dev VM trust model where the operator already
has Windows-host admin to reach the VM at all.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: Kabuki94

usr/libexec/mios/mios-dashboard.sh

@@ -146,8 +146,9 @@ print_endpoints() {
         "$(ep_dot http://localhost:3000/api/v1/version)" "$C_D" "$C_R"
     printf '    %s  AI          %shttp://localhost:8080/v1%s   %s%s%s\n' \
         "$(ep_dot http://localhost:8080/v1/models)" "$C_D" "$C_R" "$C_GRY" "$MIOS_AI_MODEL" "$C_R"
-    printf '    %s  Cockpit     %shttps://localhost:9090/%s\n' \
-        "$(ep_dot https://localhost:9090/)" "$C_D" "$C_R"
+    printf '    %s  Cockpit     %shttps://localhost:9090/%s   %slogin: %s / %s%s\n' \
+        "$(ep_dot https://localhost:9090/)" "$C_D" "$C_R" \
+        "$C_GRY" "${MIOS_LINUX_USER:-mios}" "${MIOS_DEV_DEFAULT_PASSWORD:-mios}" "$C_R"
     printf '    %s  Ollama      %shttp://localhost:11434%s\n' \
         "$(ep_dot http://localhost:11434/)" "$C_D" "$C_R"
 }