fix(hy-check): close place-call, paren-callee, and A3/const bypasses (fixes #500)

[gelismarvel]

Summary

Fixes #500

Closes five soundness gaps in hy-check where calls and closures inside Stmt::Assign target places, parenthesized callees, A3 closure/method/inline-FnLit callees, and shadowed builtins (delete, copy, len, cap, print, println, make, new, append, close) bypassed HYB-E3003, HYB-E3006, HYB-E3102, and HYB-E2005:

1. walk::own_calls, walk::own_fnlits, and process_assign target-place traversal (walk.rs, loans.rs, closures.rs, builtins.rs):
   • Extend walk::own_calls to recurse into Stmt::Assign target places (PlaceKind::Index, PlaceKind::Field, PlaceKind::AddrOf) via expr_calls_in_place so calls nested inside LHS index expressions (e.g. arr[copy(dst, src)] = 1, arr[delete_helper(m)] = 1) are visited by process_call, check_builtin_call, A3 interprocedural mutation scans, and T22 const-mutation scans.
   • Add walk::own_fnlits / walk::expr_fnlits and invoke check_closure_captures on PlaceKind::Index index expressions inside process_assign so inline closures inside LHS index expressions are checked for capture/sendability/const-write rules.
2. Parenthesized callee unwrapping (loans.rs, builtins.rs, closures.rs):
   • Use unwrap_parens(cr.callee) across resolve_call, call_mutates_param, collect_mutation_roots, call_mutates_const_param, check_builtin_call, and expr_contains_spawn_or_send so (copy)(dst, src), (delete)(m, k), and (mutator)(m) are not misclassified as Resolved::None or non-builtin calls.
3. A3 interprocedural & closure/method/inline-FnLit callee soundness (loans.rs, model.rs):
   • Track per-parameter mutation indices for local closures in FnState::closure_param_mutates (with scope stack closure_param_scopes in FnState::scope_push / scope_pop) and check them via check_a3_closure_param_conflict.
   • Check method calls (Resolved::Method -> check_a3_method_conflict) and inline FnLit / computed expression callees (Resolved::None -> check_a3_inline_or_expr_call) against live A3 map-slot loans, using LexicalStructMap to disambiguate receiver struct types while failing closed when a receiver or callee cannot be statically narrowed.
4. Shadowed builtin & package-name disambiguation (builtins.rs, loans.rs):
   • Guard builtin checks (delete, copy, A3_PURE_FNS, A3_PURE_PKGS, and check_builtin_call arity/type checks) with self.lookup_binding(st, name).is_none() and lexical shadow tracking so local variables or parameters named delete, copy, len, fmt, etc. neither trigger false-positive builtin diagnostics nor grant A3_PURE_FNS / A3_PURE_PKGS exemptions to mutating closures.
5. T22 const deep-immutability (HYB-E3006) across Match, Select, and non-Ident callees (loans.rs):
   • Extend stmt_mutates_const_param and call_mutates_const_param to traverse Stmt::Match and Stmt::Select arms, method calls, inline FnLit calls, and unknown/closure callees (failing closed when a const-aliased reference is passed).

Verification

• Added 14 regression and positive-control tests in compiler/crates/hy-check/tests/place_call_and_a3_callee_soundness.rs.
• cargo test --manifest-path compiler/Cargo.toml -p hy-check passes completely (137/137 unit tests + 14/14 place_call_and_a3_callee_soundness + all integration test suites, 0 warnings).

[gelismarvel]

Closing this PR. On review, its changes substantially duplicate the earlier PR #501 by @o2splatform-cmyk, so it should not have been submitted as separate work. Withdrawing it (and any bounty claim attached to it) in favor of the original. Apologies for the noise.