fix(parsers): recognize computed variable usage reads

[user-github-me]

Studio's variable usage report misses reads through window.__hyperframes["getVariables"]() and can confidently label those declarations unused. It also skips a values alias used as the computed key of another object, leaving scanIncomplete false despite the value escaping.

Recognize a literal "getVariables" member name and skip property-position identifiers only for noncomputed members. Bracket getter reads now cross-reference declared and undeclared ids like dot calls; computed-key escapes mark the existing report incomplete.

Validation:

• Six scanner and two SDK regressions fail on main; two additional controls preserve ordinary property-name handling.
• Full parser suite: 1,240 passed, 4 skipped, 3 todo. Full SDK suite: 593 passed.
• Built SDK browser bundle verifies bracket/dot report equality, alias reads, and dynamic-access degradation in Chromium with no browser errors.
• Parser/SDK builds and type checks, repository lint/format, pre-commit gates, comment checks, deletion guard, and test reachability pass.

[jrusso1020]

Thanks for the careful write-up. The documented ways to read variables are the dot-call forms the scanner already covers, and we haven't seen a bracket-string getter or the values object used as a computed key in real compositions, so we'd rather not grow the scanner for those cases. Happy to revisit if a real composition hits it. — Rames