refactor(ts-transformers): optimize when/unless based on right-side cost

[mathpirate]

Changes the decision logic for when to use when/unless helpers:

• Previously based on whether LEFT side was a simple opaque ref access
• Now based on whether RIGHT side is "expensive" (JSX or needs derive)

This better captures the intent: when/unless provide short-circuit optimization that's most valuable when the right side is expensive to construct (like JSX) or when both sides need derive (for taint tracking).

Key changes:

• Add isJsxExpression() helper to detect JSX elements/fragments
• Use when/unless only when: rightIsJsx OR rightNeedsDerive
• Simple refs passed directly to when/unless (no derive wrapper)
• String/number literals on right side → plain derive, no short-circuit

---

Summary by cubic

Optimized when/unless usage to only short-circuit when the right-hand side is expensive (JSX or needs derive), reducing unnecessary derive wrapping and matching actual runtime cost.

• Refactors
  • Added isJsxExpression() to detect JSX elements and fragments.
  • Use when/unless only when the right side is JSX or has reactive deps; otherwise wrap the whole expression in derive.
  • Pass simple opaque refs directly as the condition; derive complex left conditions when needed.
  • Keep string/number literals on the right inside derive (no short-circuit).
  • Avoid re-wrapping when/unless/computed calls in derive.
  • Updated fixtures and tests for &&, ||, ?? chains and map callbacks to reflect the new selection logic.

^{Written for commit 070b7b2. Summary will update automatically on new commits.}

[cubic-dev-ai]

No issues found across 10 files

[seefeldb]

this is called from within a derive here? that's a bit redundant taint-wise * uncomplicating jsx. i wonder what triggered that.