feat: vss ldk debug ui

[ovitrif]

This PR:

1. Adds VSS LDK key management to the LDK Debug screen with list, delete, and export/share actions
2. Organizes the VSS section into App and LDK tabs for clearer separation
3. Refactors calculateTotalFee to use the Result API instead of try-catch

Description

Extends the LDK Debug screen with a tabbed VSS section separating App-level and LDK-level keys. The LDK tab supports listing all tagged keys, deleting individual keys by namespace, and exporting key values as shareable files via FileProvider. Also adds an exports cache path for file sharing and makes icon sizes configurable in SettingsTextButtonRow.

Preview

QA Notes

1. VSS tabs

• Open Dev Settings > VSS
• Verify the VSS screen shows App and LDK tabs
• Tap each tab and confirm the UI switches correctly

2. List LDK keys

• Select the LDK tab
• Tap "List Keys"
• Verify keys are listed with index, version, and key name
• Verify the count badge updates

3. Delete LDK key

• From the listed LDK keys, tap the trash icon on a key
• Verify the key is removed from the list
• Verify a toast confirms the deletion

4. Export/share LDK key

• From the listed LDK keys, tap the share icon on a key
• Verify the system share sheet appears with the exported file
• Verify the saved files is not blank

5. App tab unchanged

• Switch to the App tab
• Verify List Keys, individual delete, and Delete All work as before

[jvsena42]

tAck

The base branch was changed.