Crash fixes, reorg handling, and sync performance improvements

- Fix FFI panics with catch_unwind and safe CString construction
- Handle poisoned mutex/RwLock after prior panics instead of crashing
- Fix empty block list panics in clear_blocks and invalidate_block
- Reuse Tokio runtime across block fetch batches to reduce overhead
- Add fetch_blocks_with_runtime for caller-managed runtime lifecycle
- Update branding, dependencies, and checkpoints for DragonX

.gitignore

@@ -1,7 +1,7 @@
-target/
-.vscode/
-history.txt
-/.idea/
-tarpaulin-report.html
-/log*
-silentdragonlite-cli
+target/
+.vscode/
+history.txt
+/.idea/
+tarpaulin-report.html
+/log*
+silentdragonlite-cli