Add Text localization support

[Kyle-Ye]

Agent Summary

• Add localized Text storage backed by LocalizedStringKey.
• Support bundle, table, and locale-aware lookup for localized strings and attributed strings.
• Resolve localized string interpolation for primitive values, Foundation formatters, format styles, Text, AttributedString, and localized string resources.
• Preserve sentence-boundary capitalization behavior for interpolated text.
• Add SPI coverage for sentence-boundary localization behavior.
• Document the public localized text APIs.

[augmentcode]

🤖 Augment PR Summary

Summary: This PR introduces localized Text storage backed by LocalizedStringKey, enabling locale-aware string lookup and interpolation.

Changes:

• Implements LocalizedStringKey resolution into resolved text containers, with support for bundle/table lookup and optional Markdown-attributed localization on Darwin.
• Adds interpolation plumbing for primitive values, Foundation formatters, format styles, Text, AttributedString, and (Darwin-only) LocalizedStringResource.
• Introduces sentence-boundary capitalization context tracking via a new environment value (Darwin-only) and an SPI helper to detect sentence starts.
• Adds SPI overlays for localized string / attributed string lookup and sentence-boundary detection (_LocalizeString, _LocalizeAttributedString, _isBeginningOfSentence).
• Updates resolved text attachment markers to use a shared String.nsAttachment constant.
• Exposes Text._localizationInfo based on underlying storage for introspection.
• Adds an SPI test covering sentence-boundary detection behavior.

Technical Notes: The implementation includes Darwin-only code paths for attributed localization and capitalization context, with non-Darwin fallbacks using Bundle.localizedString(forKey:...).

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[augmentcode]

Review completed. 3 suggestions posted.

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 387 lines in your changes missing coverage. Please review.
✅ Project coverage is 26.75%. Comparing base (e3b18c6) to head (cba9a9c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...penSwiftUICore/View/Text/Text/Text+Localized.swift	0.00%	354 Missing ⚠️
...enSwiftUICore/View/Text/Resolve/ResolvedText.swift	0.00%	8 Missing ⚠️
...xt/CapitalizationContextDependentFormatStyle.swift	0.00%	8 Missing ⚠️
Sources/OpenSwiftUICore/View/Text/Text/Text.swift	0.00%	5 Missing ⚠️
...Core/View/Text/Text/Text+DiscreteFormatStyle.swift	0.00%	4 Missing ⚠️
...penSwiftUICore/View/Text/Text/Text+Formatter.swift	0.00%	4 Missing ⚠️
...nSwiftUICore/View/Text/Util/String+Extension.swift	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #885      +/-   ##
==========================================
- Coverage   26.93%   26.75%   -0.18%     
==========================================
  Files         679      682       +3     
  Lines       47281    47612     +331     
==========================================
+ Hits        12735    12739       +4     
- Misses      34546    34873     +327     

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