test: add comprehensive edge case coverage for template_renderer

- Add 13 new test cases covering all critical missing scenarios
- Add error handling tests for all 3 ProvisionTemplateError variants
- Add input validation tests for empty names, special chars, unicode
- Add file system edge cases for existing dirs, permissions, duplicates
- Add async operation tests for concurrency and partial failures
- Fix clippy warnings and improve code documentation
- All 189 unit tests + 4 integration tests + 3 doc tests passing
- All linters passing (clippy, rustfmt, shellcheck, markdown, yaml)

Author: josecelano

src/actions/mod.rs

@@ -19,7 +19,7 @@ pub enum RemoteActionError {
         action_name: String,
         message: String,
     },
-    
+
     /// Action execution failed with custom error
     #[error("Action '{action_name}' execution failed: {message}")]
     ExecutionFailed {

src/ssh.rs

@@ -16,7 +16,7 @@ pub enum SshError {
         attempts: u32,
         timeout_seconds: u32,
     },
-    
+
     /// Underlying command execution failed
     #[error("SSH command execution failed: {source}")]
     CommandFailed {