Graph recursion made stack-safe for very large dependency graphs

tuist generate no longer crashes on large valid acyclic dependency graphs. Recursive graph traversals in CircularDependencyLinter, GraphCircularDetector, the local topologicalSort, ModuleMapMapper, and StaticProductsGraphLinter have been replaced by iterative implementations that use explicit stacks, so deep dependency chains no longer grow the Swift call stack. Diagnostics for circular dependencies and existing caching/ordering/linting behaviour are preserved.