bug: opaque keyring error on headless Linux; no guidance to use file session backend

[Balestrino]

Describe the bug

On a headless Linux host with no D-Bus Secret Service running, sc login fails after the device-code step with a raw, unactionable error:

Error: Platform secure storage failure: DBus error: The name org.freedesktop.secrets was not provided by any .service files

Nothing in the output tells the user that a file-based session backend exists (session_backend = "file" under [auth] in config.toml), so the CLI appears broken on servers/VMs/containers without a desktop keyring.

Steps to reproduce

1. On a headless Linux box (no gnome-keyring / Secret Service on the session bus).
2. Run sc login and complete the device-code verification in a browser.
3. Login fails when persisting the session to the OS keyring.

Expected behavior

When the OS secret service is unavailable, the error should be actionable telling the user they can set session_backend = "file" under [auth] in config.toml and retry. (A file backend already exists; the failure just isn't discoverable.)

Actual behavior

Error: OS secret storage (keyring/Secret Service) is unavailable. Store the session in a local file instead: add `session_backend = "file"` under `[auth]` in /home/user/.config/scalable-cli/config.toml, then run 'sc login' again.

[auth]
session_backend = "file"

Caused by:
  Platform secure storage failure: DBus error: The name org.freedesktop.secrets was not provided by any .service files
  DBus error: The name org.freedesktop.secrets was not provided by any .service files
  The name org.freedesktop.secrets was not provided by any .service files

CLI version

sc 0.3.0 — Linux (headless, no Secret Service)

Install method

Homebrew

OS and version

Debian 11

Architecture

x86_64

Shell

bash

Command

sc login

Output mode

Human

Logged in before running the command

Yes

Broker context selected

Yes

Additional context

No response

Checklist

• I have searched existing issues.
• I am using the latest available version of the CLI.
• This is about the Scalable CLI, not an account, trading, payment, or broker support request.
• I have removed tokens, IDs, and personal financial data.

[Balestrino]

i cant open PR on this repo but i've implemented and tested a fix:

Balestrino@a85fada