fix(studio): cover GSAP editor target-resolution limitations (#1116)

Follow-up to #1115. Makes the Design-panel editor recognise every target
shape real compositions use. The panel stays behind STUDIO_GSAP_PANEL_ENABLED
(default off) — no flag change here.

- Array targets: tl.to([a, b], {...}) resolves to a CSS group selector
  (".a, .b"). The source array is never rewritten — the joined string is for
  display/matching only; edits still touch just the vars object.

- Chained calls: tl.to(a, ...).to(b, ...) — the matcher now walks the member
  chain to its timeline root, so every link is captured (previously only the
  first). Deletion is chain-aware: it splices out the single targeted link and
  re-points the chain instead of dropping the whole statement.

- gsap.utils.toArray("sel") resolves like querySelectorAll, inline or via a
  variable binding.

- Lexical scoping: element-variable resolution is now per-scope (walks the
  enclosing function/program chain) instead of a flat map. Fixes silent
  wrong-resolution when two IIFEs reuse a variable name, and unlocks
  multi-scene files. (Addresses review: flat-binding-scope.)

- forEach/map callback params (items.forEach(el => tl.to(el, …))) and items[i]
  indexing resolve to the collection's selector, so loop-generated tweens are
  editable.

- Panel matching: an element matches a tween when its id/selector is any member
  of a comma-group target, so either element of an array/toArray tween surfaces
  the shared animation.

- Review items: mutation parse failures now console.warn instead of swallowing
  silently; buildTweenStatementCode no longer emits duration on `set`; the
  id-only serialize-side filter is renamed getAnimationsForElementId to
  disambiguate from the panel's id-or-selector matcher; added fromTo round-trip
  and variable-target overlap-lint tests.

Genuinely runtime-only targets (template-literal selectors, unbounded loops)
still skip gracefully — they can't be resolved or matched statically.