feat: initial implementation of agents_dashboard v0.1.0

Panels: Connection + Agents + Logs + Status Feed.
- HTTP GET /agents + POST /agents/{id}/{start,stop,restart}
- SSE streaming: /sse/agents/{id}/logs + /sse/status
- DPAPI/XOR credential storage in local_files/agents_dashboard.db
- data_table style agents table with filter + status icons
- SQLite migrations via sqlite3_exec at startup
- --self-test mode: db + secret_store round-trip + subsystem checks
- pytest mock server emulating agents_and_robots API

Registry functions: http_request_cpp_core, sse_client_cpp_core,
  secret_store_cpp_infra, logger_cpp_core
App icon: robot phosphor violet-500 (#8b5cf6)

Issue: 0129
Co-Authored-By: fn-orquestador <noreply@fn-registry.local>

CMakeLists.txt

@@ -0,0 +1,22 @@
+add_imgui_app(agents_dashboard
+    main.cpp
+    # Registry functions (issue 0129):
+    ${CMAKE_SOURCE_DIR}/functions/core/http_request.cpp
+    ${CMAKE_SOURCE_DIR}/functions/core/http_get_json.cpp
+    ${CMAKE_SOURCE_DIR}/functions/core/sse_client.cpp
+    ${CMAKE_SOURCE_DIR}/functions/infra/secret_store.cpp
+)
+
+target_include_directories(agents_dashboard PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    ${CMAKE_SOURCE_DIR}/vendor      # nlohmann/json.hpp
+)
+
+# fn_table_viz: optional — guards keep the app compilable without it.
+if(TARGET fn_table_viz)
+    target_link_libraries(agents_dashboard PRIVATE fn_table_viz)
+endif()
+
+if(WIN32)
+    set_target_properties(agents_dashboard PROPERTIES WIN32_EXECUTABLE TRUE)
+endif()