Introduce a distinction between base values (set via `/set` or
declarations) and active modifiers (applied via tags). This ensures
tag transitions and numeric modifiers are calculated correctly during
cascades.
- Refactor `VariableView` to use a flat list with hover popups for
declarations and active modifiers.
- Update `command-dispatcher` to use `getCombined` for accurate
value lookups and `setBase` for variable updates.
- Update `var-reactivity` to manage `baseValues`, `activeMods`, and
`sourceActivations` separately.
- Export new utility functions for accessing combined values,
modifiers, and declaration expressions.