Routines: add setting to set Calendar as the default tab

Feature request

Current behavior:
The Routines view always opens on the "All" tab. The "Calendar" tab must be clicked manually every time.

Desired behavior:
Add a user preference (e.g. in Settings or as a persistent tab selection) to set "Calendar" as the default tab when opening the Routines view.

Why this matters:
The Calendar view is often more useful for users who want to see upcoming scheduled runs in a timeline view rather than a flat list. Having to switch tabs on every visit creates unnecessary friction.

Possible implementation:

• Remember the last active tab per user session, or
• Add a toggle/setting: "Default Routines view: All / Calendar"

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