修复 SQL 编辑器表名高亮丢失

[zipg]

问题

SQL 编辑器中的有效表名在部分内置主题或长 SQL 文件中没有稳定显示表名颜色：滚动后可能退化为普通文本颜色，切换标签后也可能出现高亮缺失。

修复

• 为内置 CodeMirror 主题提供表名颜色兜底，避免编辑器专用 CSS 变量未定义时退化为普通文本色。
• 对首次打开且长度受控的 SQL 文档预热完整语义高亮，减少滚动到新区域才临时着色的现象。
• 语法树尚未准备好时保留已有装饰，避免一次增量计算清空现有高亮。

验证

• pnpm exec vitest run apps/desktop/src/lib/__tests__/editorThemes.spec.ts apps/desktop/src/lib/__tests__/editor/queryEditorSemanticHighlightPerformance.spec.ts：21 项通过。
• pnpm typecheck：通过。
• 本地开发页面实测 query_12.sql 滚动前后表名保持橙色高亮。

Fixes #8942

[t8y2]

Thanks — both mechanisms in this PR match the two root causes of #8942. I pushed one follow-up commit (1ee0dbf7) to close a crash path and a perf gap:

1. buildDecorations now returns this.decorations when the syntax tree isn't ready, but its first call happens from the constructor where that field is still unassigned — returning undefined throws inside CodeMirror's decoration pipeline (RangeSet.compare reads set.maxPoint). Realistic trigger: >128K documents with a cold parser (25ms ensureSyntaxTree budget) crash at mount, and even surviving that would throw on the first keystroke in update(). The constructor now initializes this.decorations = Decoration.none first.
2. The full-document prewarm re-ran after every edit (the window cache is cleared on each doc change), turning steady-state highlighting cost from O(viewport) into O(document). It's now gated behind a one-shot per-document flag, with a regression assertion added to the perf spec.

Both existing specs stay green (22/22 locally).

[t8y2]

Thanks for the contribution! Merged in 6694e43, will be released in the next version.