feat(engine): reassign stolen containers during bottom-up matching

[HarshK97]

Problem

1. Bottom-up AST matching processes nodes from leaves up to the root. When a surrounding block like an if statement gets deleted, inner blocks inside the if can greedily claim the outer function body's container because they share common leaf statements.
2. So the actual outer function body container is left unmapped, which forces the edit-script generator to emit a flood of spurious Move actions for all sibling statements.

What Changed

• Added ContestContainers in internal/engine/bottom-up.go to reassign containers claimed by nested inner T1 nodes back to their proper outer T1 parent.
• Updated Mapping.Remove in internal/engine/mapping.go so m.Pairs stays in sync when mappings are reassigned.
• Called ContestContainers inside Match in internal/engine/matcher.go right after bottom-up matching finishes.
• Updated golden test fixtures (go_gin_fix_lint, py_requests_refactor_prefer, and rust_tokio_test_tests_when) because the redundant move and delete/insert actions are now gone.

Visual Comparison

• Example : tests/testdata/go_gin_fix_lint

Before

After