Develop - #5

Add keep.xml to preserve tx_auto_* string resources accessed via
getIdentifier() at runtime (invisible to static shrinker analysis).
Add locale_config.xml for Android 13+ per-app language support.

Product IDs use underscores (remove_ads_lifetime, pro_features_lifetime),
not dashes which are offer IDs. offerToken is optional for INAPP products
so treat null as empty string instead of aborting the purchase flow.

BiometricKeyStore now accepts configurable prefs name and keystore alias
so a separate decoy biometric store can coexist with the main one.
AppPreferences and UiState track decoy biometric enabled state.
MainActivity wires enrollment and unlock for the decoy key, deriving
the decoy master key from the decoy PIN via VaultKeyManager.

In UnlockScreen the fingerprint button uses long press for decoy unlock
and normal tap for the real vault. Settings shows a decoy biometric
section when the decoy vault is enabled.

Decoy settings are hidden by default and revealed by tapping the NULVEX
logo six times. Each tap fires one lightning bolt emoji in a random
direction; on the sixth tap all bolts explode outward and the section
becomes visible.

Register MIME types for .nulvex, .nulvxbk and .nulvxkeys files so the
app appears as a handler in file managers. Include file:// fallbacks for
legacy file managers and an autoVerify deep link for androidircx.com
media URLs. Also wire localeConfig for Android 13+ per-app language.

Add missing imports for VaultProfile and Compose offset to resolve
unresolved references that were breaking assembleDebug.

Align billing tests with updated product IDs and one-time purchase token
handling, and add coverage for single-note share imports, decoy biometric
state toggles, and manifest intent filters for encrypted files/deep links.

Allow creating labels without assigning them to a note by persisting custom
labels in app settings and surfacing them in the labels menu/filter list.
Also extend note-detail editing to update expiry alongside text and cover
both flows with updated instrumentation tests.

Extend note detail editing to support adding/removing labels and attaching
new images in the same save flow as text and expiry updates. Wire the new
save callback through MainScreen and MainActivity, and keep instrumentation
coverage stable by removing a flaky async assertion.