feat: output continuous spaces as &nbsp

[wuyiping0628]

将连续空格转为不间断空格，以便 innerHTML 输出   并在预览中保留间距
修改前：

修改后：

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our Commit Message Guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

Summary by CodeRabbit

• New Features
  • Enhanced whitespace handling in the editor with context-aware automatic conversion of spaces to non-breaking spaces for improved HTML formatting consistency.
  • Better spacing preservation during typing to ensure consistent formatting output across various content scenarios.

[coderabbitai]

Walkthrough

This PR introduces whitespace preservation utilities for the editor to maintain consistent spacing in HTML output. Two utility functions are added to handle non-breaking space conversion and decision logic, integrated into keyboard handling via a new space-key binding, and consolidated with existing clipboard processing by removing a duplicate implementation.

Changes

Whitespace Preservation Feature

Layer / File(s)	Summary
Whitespace preservation utilities packages/fluent-editor/src/config/editor.utils.ts	Introduces replaceStrWhiteSpace to convert regular spaces into non-breaking spaces based on position, and shouldInsertNbspOnSpace to determine whether a space keypress should preserve whitespace based on the preceding character.
Keyboard binding and clipboard consolidation packages/fluent-editor/src/themes/snow.ts, packages/fluent-editor/src/modules/custom-clipboard.ts	snow.ts imports the utility and adds a keyboard binding for the space key that conditionally inserts non-breaking spaces. custom-clipboard removes its local replaceStrWhiteSpace implementation and imports the shared version from editor.utils.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

A rabbit's delight, spacing made right! ✨
Where spaces transform to nbsp with might,
Keyboard bindings dance, clipboard takes flight—
HTML preserved, no more formatting blight! 🐰

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: converting consecutive spaces into non-breaking space entities ( ) in the editor output.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch wyp/space-0515

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[coderabbitai]

🧹 Nitpick comments (1)

packages/fluent-editor/src/config/editor.utils.ts (1)

116-149: ⚡ Quick win

Add focused unit tests for whitespace edge cases.

These rules are easy to regress; please add direct tests for line-start spaces, consecutive in-text spaces, full-width spaces (\u3000), and prefixes ending with \u00A0.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@packages/fluent-editor/src/config/editor.utils.ts` around lines 116 - 149,
Add focused unit tests for replaceStrWhiteSpace and shouldInsertNbspOnSpace
covering edge cases: assert replaceStrWhiteSpace turns leading spaces at
line-start into '\u00A0', handles consecutive in-text spaces by alternating
between normal space and '\u00A0' per the algorithm, correctly processes
full-width space '\u3000' as whitespace, and preserves/outputs '\u00A0' where
expected; also add tests for shouldInsertNbspOnSpace with empty prefix, prefixes
ending in regular space, prefixes ending in '\u00A0', and prefixes ending in
'\u3000' to verify true/false returns match the WHITE_SPACE_OR_NBSP_RE logic.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@packages/fluent-editor/src/config/editor.utils.ts`:
- Around line 116-149: Add focused unit tests for replaceStrWhiteSpace and
shouldInsertNbspOnSpace covering edge cases: assert replaceStrWhiteSpace turns
leading spaces at line-start into '\u00A0', handles consecutive in-text spaces
by alternating between normal space and '\u00A0' per the algorithm, correctly
processes full-width space '\u3000' as whitespace, and preserves/outputs
'\u00A0' where expected; also add tests for shouldInsertNbspOnSpace with empty
prefix, prefixes ending in regular space, prefixes ending in '\u00A0', and
prefixes ending in '\u3000' to verify true/false returns match the
WHITE_SPACE_OR_NBSP_RE logic.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 09a53e87-f240-4058-8f64-547afd7b6531

📥 Commits

Reviewing files that changed from the base of the PR and between c7f8992 and 22a6cf6.

📒 Files selected for processing (3)

• packages/fluent-editor/src/config/editor.utils.ts
• packages/fluent-editor/src/modules/custom-clipboard.ts
• packages/fluent-editor/src/themes/snow.ts