fix: reject shadowed terminal array element calls

[luisleo526]

Summary

• reject direct terminal and adjacent identity-alias temporary-array element calls when the callee is shadowed by a function parameter, immediate local, or tuple binding
• evaluate lexical bindings at the exact read program point before AST visitation, so producer order cannot leave partial analyzer state
• keep expired nested-block bindings and self-named alias initializers valid
• remove the post-body raw-symbol alias guard that could misread expired bindings

This also corrects the alias false rejection exposed after #87. The direct defect and alias program-point defect can mask each other, so they were validated as independent factors.

Exhaustive masking matrix

Complete 2^2 run, no early stop:

Cell	Direct factor	Alias factor	Result
00	off	off	both defects reproduced
10	on	off	direct fixed only
01	off	on	alias fixed only
11	on	on	both fixed

• 4 planned / 4 completed / 4 passed / 0 skipped
• publication gate: true
• fingerprint: 200465f22a7f47a69e918c0fd1b202266bcb3021b5451f4b8a24ee449db30819
• 20 fixed-lane negatives produced the exact single analyzer diagnostic with zero analyzer state
• 32 positive controls compiled and passed all structural assertions
• the 11 production file is byte-identical to the reviewed candidate: f19ba62022d5bde3241d9bb80d63cb3dcc3c7080d6bb35ade09f0bafa5bea8b5
• reviewed diff: 1953ee0f27ef640ae2b3905a077234cf814e4a8bd3542ae06a49b419d67919a4

Validation

• focused generalized cases: 27/27
• forward-local suite: 52/52
• terminal-array suite: 163/163
• full native suite: 1,596 passed / 379 skipped
• clean engine + private corpus integration: 2,134 passed / 94 skipped
• standalone corpus compilation: 254/254
• Pyodide parity: 277/277 (263 expected success, 14 expected error)
• exact 915-source differential: base 902 success / 13 error, candidate 902 / 13, zero differences
• release selftest: 8 comparator cases + 10 verdict cases
• py_compile: 120/120
• git diff --check: clean

The accepted validation board is unchanged; this is a score-neutral compiler correctness fix.