fix(rust): remove unused imports, variables, and dead code causing CI build failures

- Remove unused imports: AtomicBool, Future (provider.rs), debug (executor.rs)
- Remove unused import WorkflowScript (workflow.rs)
- Remove unused variables: tool_name, t_ctx, t_args (executor.rs)
- Remove dead variable class_indent (semantic_search.rs)

CI was failing with 'error: could not compile zesdex-infrastructure
due to 10 previous errors' caused by -D warnings treating unused
code as compilation errors.

apps/infrastructure/src/tools/semantic_search.rs

@@ -872,7 +872,6 @@ fn extract_python(content: &str, rel_path: &str) -> Vec<CodeSymbol> {
     // Track current class for method nesting
     // Reset when we see a non-indented line outside a class.
     let mut current_class: Option<String> = None;
-    let mut class_indent: Option<usize> = None;
 
     for (i, line) in lines.iter().enumerate() {
         let line_num = i + 1;
@@ -882,14 +881,12 @@ fn extract_python(content: &str, rel_path: &str) -> Vec<CodeSymbol> {
         // Reset class tracking when we leave its indentation level.
         if current_class.is_some() && indent == 0 && !trimmed.is_empty() {
             current_class = None;
-            class_indent = None;
         }
 
         // Class
         if let Some(caps) = r.py_class.captures(trimmed) {
             let name = caps.get(1).unwrap().as_str().to_string();
             current_class = Some(name.clone());
-            class_indent = Some(indent);
             symbols.push(CodeSymbol {
                 name,
                 kind: SymbolKind::Class,