[FEATURE] Deliver the five-minute getting-started journey #407

Outcome

A practitioner can move from the public getting-started entry point to a successful AURA run against real data in under five minutes on a supported platform.

Journey

1. Find the supported install path without choosing an artifact.
2. Install and invoke aura.
3. Start from a batteries-included configuration.
4. Run /mcp add and choose a supported curated or custom MCP server.
5. Provide credentials through the guided flow.
6. Verify the connection and discovered tools before saving.
7. Grant the tools only to the worker roles that need them.
8. Restart AURA so the new configuration takes effect.
9. Run the suggested starter prompt against real data.

Acceptance criteria

• The happy path is documented as one coherent journey.
• Supported prerequisites and credentials are stated before the user begins.
• The guide reflects that /mcp add is currently a standalone-mode workflow.
• Connection failure identifies a concrete recovery action.
• Worker access is explicit and follows least privilege.
• The required restart is stated at the point it is needed.
• The first streamed response does not present unexplained dead air.
• Internal demos and onboarding use this journey rather than cloning the repository or building from source.
• A timed validation on each supported platform demonstrates that the median happy path is under five minutes.

Related epics: #212, #309, #310
Parent epic: #311
Initiative: #370