feat: improve mobile native impl (#14481)

fix #13529 

#### PR Dependency Tree


* **PR #14481** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Mobile blob caching with file-backed storage for faster loads and
reduced network usage
* Blob decoding with lazy refresh on token-read failures for improved
reliability
  * Full-text search/indexing exposed to mobile apps
* Document sync APIs and peer clock management for robust cross-device
sync

* **Tests**
* Added unit tests covering payload decoding, cache safety, and
concurrency

* **Dependencies**
* Added an LRU cache dependency and a new mobile-shared package for
shared mobile logic
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/mobile-native/src/error.rs

@@ -0,0 +1,19 @@
+use affine_nbstore::error::Error as NbStoreError;
+
+#[derive(uniffi::Error, thiserror::Error, Debug)]
+pub enum UniffiError {
+  #[error("Error: {0}")]
+  Err(String),
+  #[error("Base64 decoding error: {0}")]
+  Base64DecodingError(String),
+  #[error("Timestamp decoding error")]
+  TimestampDecodingError,
+}
+
+impl From<NbStoreError> for UniffiError {
+  fn from(err: NbStoreError) -> Self {
+    Self::Err(err.to_string())
+  }
+}
+
+pub(crate) type Result<T> = std::result::Result<T, UniffiError>;