Feat/zpl mu units of measure - #128

Curried dot-helper plumbing:
- helpers.ts gains `dotsFor(state)` which binds intDots/intDotsOrUndef
  to a state's live unitScale. Replaces a per-factory closure that
  was duplicated across fields/barcodes/graphics/labelConfig.
- intDots collapses to a thin fallback wrapper over intDotsOrUndef
  (DRY: one parseFloat+NaN+round body, not two).

Factory-signature unification:
- createSetupScriptHandlers(s), createLabelConfigHandlers(s, dpmm) and
  createBarcodeHandlers(s) now take ParserState, matching the existing
  createFieldHandlers/createGraphicsHandlers pattern.
- ^A dynamic-font dispatch fallback moves out of zplParser.ts into a
  named export `handleDynamicFontA` in fields.ts. Orchestrator still
  owns the `cmd[0]==='A'` wildcard match.
- New units.ts handler factory owns the ^MU command (both unitScale
  format-state mutation and muResampling labelConfig persistence).

Schema reshape:
- formatDpi/outputDpi individual optionals → `muResampling: { formatDpi,
  outputDpi } | undefined` paired sub-object. Type-enforces the
  spec's "both or neither" invariant; parser persists only when both
  slots arrive valid, generator emits the pair without half-set guards.

Correctness:
- Invalid ^MU a-slot (e.g. ^MUX) preserves prior unitScale instead
  of silently downgrading to dots. Marked partial.

FormatState.unitScale documented as the one slot that intentionally
survives ^XA per ^MU spec; per-block isolation comes from
zplImportService calling parseZPL per ^XA block.

The ^A{font} dynamic-font command can't live in the exact-match
handler table because the font char is part of the command key.
Previously it leaked through as a named-export helper plus an
orchestrator-side inline `cmd[0]==='A' && cmd.length===2` check.

Introduces a `Wildcard` type (matches + handle) so the pattern-match
logic stays with its owning handler module. `createDynamicFontAWildcard`
in fields.ts now declares the pattern; the orchestrator collects
wildcards into a list and falls back to them only after exact-match
dispatch fails, so a registered handler always wins.

Handler signature gains `cmd: string` as a third argument so wildcards
can inspect the matched command key (e.g. read the font char from
`cmd[1]`). Existing handlers ignore the new arg.

Removes the named-export workaround; the orchestrator no longer needs
to know about specific wildcard patterns.

^BR p[2] is a 1-10 magnification multiplier, not a dot quantity. The
parser previously wrote it into `defaults.byModuleWidth` (the shared
^BY slot, dot-typed everywhere else), so a ^BR field would silently
overwrite real dot widths from ^BY and leak the magnification value
into subsequent non-gs1 barcodes.

Parser side:
- `FieldState.gsMagnification` (1-10 or undefined) carries ^BR p[2]
  on its own slot. Reset at ^FS so a bare ^BR^FS doesn't leak.
- Out-of-range values fall back to `defaults.byModuleWidth` at flush
  time, preserving the prior "single sizing knob" semantics when ^BY
  and ^BR carry the same value (the common case).

Schema rename:
- `Gs1DatabarProps.moduleWidth` → `magnification`. The value always
  represented the ^BR multiplier semantically; the rename ends the
  confusion with the dot-typed ^BY value of the same name.
- Generator emits `magnification` to both ^BY and ^BR slots per the
  Zebra convention. Imports with mismatched ^BY/^BR values normalize
  to the ^BR slot (firmware behavior), so `^BY4 ^BR_,_,6` re-emits
  as `^BY6 ^BR_,_,6`.

Schema migration:
- designFile.parseDesignFile and labelStore persist (v5→v6) walk the
  object tree and rename `props.moduleWidth` → `props.magnification`
  for gs1databar leaves. Both routes share a new `objectTree.ts`
  walker. Migration is idempotent and preserves an existing
  magnification key.

Locale rename:
- `registry.gs1databar.moduleWidth` → `registry.gs1databar.magnification`
  across 32 locales. Display value seeded from aztec/qrcode.magnification
  ("Size (1-10)" in en) so the user-facing label matches how the rest
  of the registry names the same 1-10 knob.