Improve user-facing error messages for clarity

[SLC-BTC]

Summary

• Rewrites ~40 cryptic/technical error messages in the string catalog to use plain language with actionable guidance
• Replaces hardcoded "Device wasn't found" in LoginViewModel.kt with proper id_ localization key
• Fixes grammar issues ("Could not recognized" → "Could not recognize")
• Tones down alarming hardware wallet error message about compromise
• Adds 8 new localization keys to match iOS companion PR

Examples of changes

Before	After
"Operation failure"	"Something went wrong. Please try again or contact support if the issue persists."
"Could not recognized QR code"	"Could not recognize this QR code. Please try scanning again."
"Invalid mnemonic"	"The recovery phrase you entered is not valid. Please check and try again."
"Insufficient funds"	"You don't have enough funds for this transaction."
"Invalid status. Check that your device is unlocked and try again."	"Your device may be locked or unresponsive. Please unlock it and try again."
"Device wasn't found"	Uses id_your_device_was_disconnected localization key

Companion PR: Blockstream/green_ios#95

Test plan

• Verify app builds successfully with no missing string key references
• Exercise key error paths: wrong PIN, invalid address, disconnect hardware wallet, timeout scenarios
• Confirm new error messages render correctly in dialogs and snackbars
• Non-English translations are unchanged and will need a separate translation pass

🤖 Generated with Claude Code