fix(macros): stop marking existing macros as deleted in the settings - #3

Two issues made the macros settings mark macros as deleted or break the
list entirely:

- `allMacros` in the expert tab was filtered by the search field, but
  `existsMacro()` and `getMacroDescription()` used it for existence
  checks. Typing in the "available macros" search therefore labelled
  every non-matching macro of the edited group as a deleted macro and
  hid its color/visibility buttons. The search filter now lives in a
  separate `filteredMacros` getter used only by `availableMacros`.

- `searchMacros` is reset to null by the clearable prop of v-text-field,
  so clicking the clear icon threw on `.toLowerCase()` and broke the
  rendering of both settings tabs.

Additionally `printer/getMacros` defaulted `configfile.settings` to null
and then indexed it unconditionally, which threw when the macro objects
were known but configfile was not populated yet.

Signed-off-by: Åsmund Collin <aakjaergaard@gmail.com>

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>