Add minimum GPS accuracy preference for logging

[Andyporras]

Introduces a new user preference to set the minimum required GPS accuracy before starting to record track points. Updates the GPSLogger service to wait until the specified accuracy is achieved, and adds relevant UI strings and preference entry.

📝 Feat: Settings: minimum GPS accuracy to start recording track

🛠️ Issue

• Closes Settings: minimum GPS accuracy to start recording track #444

🛠️ Related issues (if applicable)

• N/A

📖 Description

This PR introduces a new user preference to set the minimum required GPS accuracy before starting to record track points.

Changes:

• Preferences UI: Added a new EditTextPreference in the GPS Settings menu (prefs_gps_min_accuracy) allowing users to input a value in meters (e.g., 10). Default is 0 (disabled).

• Logic Implementation: Updated GPSLogger.java to read this preference.

  • Added a "latch" mechanism (isAccuracySatisfied).
  • The service now ignores incoming location updates until one arrives with an accuracy better than or equal to the configured value.
  • Once the accuracy is met, recording starts normally for all subsequent points.

• Strings: Added necessary string resources for the new setting.

Rationale: This prevents the recording of widely inaccurate points (jumping) that often occur immediately after starting the GPS, significantly improving the quality of the track's start, especially for vertical distance computation.

🖼️ Screenshots (if applicable)

✅ Pull Request Checklist

• The PR is proposed to the DEVELOP branch.
• The changes have been tested on the target Android API and minimum Android API.
• Automated tests have been added (if applicable).
• The feature is well documented.
• There is a reference to the original ISSUE and related work.

📝 Additional Notes

The logic ensures that we only wait once at the beginning. If the GPS accuracy degrades later (e.g., entering a tunnel), the recording continues uninterrupted to avoid gaps in the track, satisfying the requirement to "wait before starting".

[jamescr]

Move preference keys and default values to OSMTracker. Preferences class. Check this commit for an example.

Min accuracy preference is numeric; consider using the setupEditTextNum() method from Preference Activity to force numeric inputs and add an option to reset to default value.

[Andyporras]

Thanks @jamescr for the review. I've just refactored the code to move the constants to OSMTracker.Preferences and implemented setupEditTextNum() for the input field validation. Ready for another look!