Fix Phase 0 compilation errors - validation fixes

Resolved 22 compilation errors:
- Fixed lib.rs re-exports to use correct submodule paths
- Added missing submodule declarations to module files
- Created stub files for referenced submodules
- Fixed main.rs imports to use lib.rs re-exports

Project now compiles successfully with only 2 expected warnings:
- dead_code warning for jobs field in JobManager
- unused_variable warning for job_manager in main

Both warnings are expected for scaffolding phase.

src/lib.rs

@@ -20,7 +20,7 @@ pub mod logging;
 pub mod packages;
 pub mod systemd;
 
-// Re-export commonly used types
-pub use config::AppConfig;
-pub use jobs::JobManager;
-pub use logging::init_logging;
+// Re-export commonly used types from submodules
+pub use config::loader::AppConfig;
+pub use jobs::manager::JobManager;
+pub use logging::init::init_logging;