- Add #[serde(default)] to unmapped_glyph_names field in UnmappedGlyphNamesConfig
- Field now defaults to empty Vec<String> when not specified in config files
- Add comprehensive integration tests covering all scenarios:
- Config without unmapped_glyph_names field (defaults to empty)
- Config with unmapped_glyph_names specified (parses correctly)
- Config with explicit empty array (works as expected)
- Minimal empty config (all fields default appropriately)
Acceptance criteria:
- ✅ unmapped_glyph_names defaults to empty list when not specified
- ✅ Default value handling integrates cleanly with existing config logic
- ✅ Code compiles without errors
- ✅ Both specified and unspecified cases work correctly (4/4 tests pass)
Closes bf-34xgg
