Optimize watch managers to skip processing when no watch is connected

[marv-out]

Watch Manager Optimizations

This PR improves app performance by preventing unnecessary processing when no watch is connected. It addresses two key issues:

Apple Watch & Garmin Watch Optimizations

Problem

The app was previously creating tasks and performing expensive calculations for watch data even when no watch was connected or the watch app wasn't installed.

Solution

1. Added early-return guards in both watch managers:

   • BaseWatchManager.setupWatchState now checks if a watch is paired, the session is reachable and the app is installed
   • BaseGarminManager.setupGarminWatchState now checks if any Garmin devices are connected

2. Optimized CoreData publishers to prevent task creation:

   • Added watch connectivity checks in all publisher callbacks
   • Tasks are only created when watches are actually connected
   • Added debug logs to indicate when processing is skipped

Performance Impact

These changes can potentially reduce CPU and memory usage when no watch is connected, as the app no longer:

• Creates unnecessary background tasks
• Performs expensive CoreData fetches
• Builds watch state objects that would never be sent

TODO

• Verifying that watch functionality works normally when watches are connected
• Confirmed that unnecessary processing is skipped when no watch is connected
• Testing both Apple Watch and Garmin devices

[dnzxy]

@t1dude (Apple watch), @mountrcg (Garmin), you both are avid watch users. Could you please give this a test, especially you @t1dude and see that this does no longer do any calls and updates to the watch manager, while keeping functionality (and especially sync after staleness) intact.

[t1dude]

...testing in vivo for a few days.

[t1dude]

Unfortunately, a bug in Watch OS 26 Beta 2 is preventing me from using the Trio watch app properly. I'll test this PR again once the Watch OS bug has been fixed, as the error is not related to this PR.

[mountrcg]

Will test tomorrow!

[mountrcg]

No issues with garmin watch so far, running 14hrs reliably atm.

[mountrcg]

still on it, garmin watch is still rocksolid - go from my side

[marv-out]

Ok. So we still need to confirm that apple watch works properly when connected without any dropouts. This was @dnzxy worry from looking at the guards