Fold logical and nullish fallbacks only when the left operand is a
constant. Host references have unknown truthiness and remain unresolved;
partial recovery retains possible fallback text and explicit HTML holes.
Follow only the selected operand when a constant condition precedes a
partial output.

Add regressions for state parsing, host properties, storage, runtime
calls, aliases, missing bindings, and constant object lookups. The state
parsing example already passes on this base; reproduce the missing
constant-object fallback folding before adding the implementation.

Validate with libbox test --filter TelegramWidgetTests|TelegramMarkupTests:
137 tests in 8 suites pass.