feat(wallet): persist history and surface pending sends

Add an encrypted SQLite transaction history cache with cached tip metadata and
per-address shielded scan progress so startup and full refreshes avoid
re-scanning every z-address while still invalidating on wallet/address/rescan
changes.

Improve wallet history loading by paging transparent transactions, preserving
cached shielded and sent rows, keeping recent/unconfirmed activity visible, and
classifying mining-address receives. Show z_sendmany opid sends immediately in
History and Overview, pin pending rows through refreshes, and apply optimistic
address/balance debits until opids resolve.

Add timestamped RPC console tracing by source/method without logging params or
results, reduce redundant refresh/RPC calls, and cache Explorer recent block
summaries in SQLite.

Expand focused tests for transaction cache encryption, scan-progress
persistence/invalidation, history preservation, operation-status parsing,
pending send visibility, and Explorer/RPC refresh behavior.

CMakeLists.txt

@@ -110,6 +110,32 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(tomlplusplus)
 
+# SQLite amalgamation - local Explorer block-summary cache
+FetchContent_Declare(
+    sqlite3
+    URL https://www.sqlite.org/2024/sqlite-amalgamation-3450300.zip
+    URL_HASH SHA256=ea170e73e447703e8359308ca2e4366a3ae0c4304a8665896f068c736781c651
+)
+FetchContent_GetProperties(sqlite3)
+if(NOT sqlite3_POPULATED)
+    FetchContent_Populate(sqlite3)
+endif()
+file(GLOB SQLITE3_AMALGAMATION_C CONFIGURE_DEPENDS
+    ${sqlite3_SOURCE_DIR}/sqlite3.c
+    ${sqlite3_SOURCE_DIR}/*/sqlite3.c
+)
+if(NOT SQLITE3_AMALGAMATION_C)
+    message(FATAL_ERROR "SQLite amalgamation source not found")
+endif()
+list(GET SQLITE3_AMALGAMATION_C 0 SQLITE3_SOURCE_FILE)
+get_filename_component(SQLITE3_INCLUDE_DIR ${SQLITE3_SOURCE_FILE} DIRECTORY)
+add_library(sqlite3_amalgamation STATIC ${SQLITE3_SOURCE_FILE})
+target_include_directories(sqlite3_amalgamation PUBLIC ${SQLITE3_INCLUDE_DIR})
+target_compile_definitions(sqlite3_amalgamation PRIVATE
+    SQLITE_THREADSAFE=1
+    SQLITE_OMIT_LOAD_EXTENSION
+)
+
 # libcurl for HTTPS RPC connections (more reliable than cpp-httplib with OpenSSL 3.x)
 if(WIN32)
     # For Windows cross-compilation, fetch and build libcurl statically
@@ -255,8 +281,10 @@ set(APP_SOURCES
     src/services/wallet_security_workflow.cpp
     src/services/wallet_security_workflow_executor.cpp
     src/data/wallet_state.cpp
+    src/data/transaction_history_cache.cpp
     src/ui/theme.cpp
     src/ui/theme_loader.cpp
+    src/ui/explorer/explorer_block_cache.cpp
     src/ui/material/color_theme.cpp
     src/ui/material/typography.cpp
     src/ui/notifications.cpp
@@ -354,8 +382,10 @@ set(APP_HEADERS
     src/services/wallet_security_workflow_executor.h
     src/config/version.h
     src/data/wallet_state.h
+    src/data/transaction_history_cache.h
     src/ui/theme.h
     src/ui/theme_loader.h
+    src/ui/explorer/explorer_block_cache.h
     src/ui/notifications.h
     src/ui/windows/main_window.h
     src/ui/windows/balance_tab.h
@@ -507,6 +537,7 @@ target_link_libraries(ObsidianDragon PRIVATE
     SDL3::SDL3
     nlohmann_json::nlohmann_json
     tomlplusplus::tomlplusplus
+    sqlite3_amalgamation
     ${CURL_LIBRARIES}
     ${SODIUM_LIBRARY}
 )
@@ -712,6 +743,7 @@ if(BUILD_TESTING)
         src/services/wallet_security_controller.cpp
         src/services/wallet_security_workflow.cpp
         src/services/wallet_security_workflow_executor.cpp
+        src/ui/explorer/explorer_block_cache.cpp
         src/ui/windows/balance_address_list.cpp
         src/ui/windows/balance_recent_tx.cpp
         src/ui/windows/console_input_model.cpp
@@ -723,6 +755,7 @@ if(BUILD_TESTING)
         src/util/payment_uri.cpp
         src/util/amount_format.cpp
         src/data/wallet_state.cpp
+        src/data/transaction_history_cache.cpp
         src/daemon/lifecycle_adapters.cpp
         src/rpc/connection.cpp
         src/resources/embedded_resources.cpp
@@ -742,6 +775,7 @@ if(BUILD_TESTING)
 
     target_link_libraries(ObsidianDragonTests PRIVATE
         nlohmann_json::nlohmann_json
+        sqlite3_amalgamation
         ${SODIUM_LIBRARY}
     )