fix(typescript): respect unified js/ts.* settings

[NamesMT]

Problem

The TypeScript service only read the deprecated per-language settings (typescript.* / javascript.*), so an embedded <script> block ignored the unified js/ts.* settings that VS Code's built-in TypeScript extension prefers.

The reported case is formatting (vuejs/language-tools#6150), but the same gap affects every setting the package reads. @HiDeoo found it while debugging js/ts.preferences.autoImportSpecifierExcludeRegexes in an Astro project, where the typescript.preferences.* spelling worked and the unified one did not.

This supersedes #126, which only covered js/ts.format.*.

Change

Add createUnifiedConfig(), which resolves the unified js/ts section and the language-specific section once, then reads each setting with the unified value taking precedence:

const config = await createUnifiedConfig(ctx, document);
config.get('format.semicolons', 'ignore');

Every language-specific read in the package now goes through it:

area	settings
formatting	js/ts.format.* (18 keys, incl. indentSwitchCase)
preferences	js/ts.preferences.*
suggestions	js/ts.suggest.*
validation	js/ts.validate.enabled
auto-closing tags	js/ts.autoClosingTags.enabled
inlay hints	js/ts.inlayHints.*

getUserPreferences() is included, which resolves the review comment. renameShorthandProperties and unstable have no unified counterpart and keep reading the language-specific section.

Why the default table

VS Code's built-in extension decides with WorkspaceConfiguration.inspect() — it knows whether a unified setting was actually modified. A language server cannot: workspace/configuration returns the resolved value with the registered default already merged in, so an unset setting is indistinguishable from one set to its default.

The helper therefore treats a unified value equal to its registered default as unset, and keeps every default in one table (unifiedDefaults) that mirrors contributes.configuration of VS Code's typescript-language-features package.json. This is the best available approach: the hardcoded-default comparison is only a heuristic, and a table is the smallest version of that heuristic — one line per changed default instead of 40 scattered ?? default sites.

I verified the table mechanically against VS Code's current package.json: all 50 keys match, and every relevant js/ts.* setting that the service reads is covered.

Remaining limitation, unchanged in kind from #126: explicitly setting a unified key to its exact default while also setting the deprecated counterpart to a different value resolves to the deprecated value. VS Code would take the unified default. This needs inspect() over the wire to fix.

Options considered:

• A custom LSP request carrying inspect(). Only correct fix. Needs a LanguageServiceEnvironment API plus a client-side handler in @volar/vscode / vuejs/language-tools, so it is out of scope here. If it lands, createUnifiedConfig is the single place to switch over.
• Prefer unified whenever the key is present. Incorrect — VS Code resolves the whole section, so this would ignore every typescript.format.* setting for users who only configured those.
• Read only the language-specific section when the unified one equals the default. That is what this PR does.

Separately, workspace/configuration is requested without a document scope, so language-scoped overrides such as "[typescript]": { "js/ts.format.semicolons": "insert" } are still not visible to the server. That is a pre-existing limitation of the host request, not of this change.

One pre-existing read is deliberately left alone: the auto-import cache's setPreferences still reads typescript.preferences. It applies to the whole language service rather than a document, so there is no language section to fall back to; moving it to js/ts.preferences would need a separate decision about which section it should use. The includeInlayParameterNameHints mapping also keeps its current behavior, where 'none' maps to undefined.

Test plan

• pnpm run build, pnpm run test, pnpm run lint, dprint check
• New specs: getUnifiedConfig, getFormatCodeSettings, getUserPreferences, covering unified precedence, fallback when the unified value equals its default, language-specific fallback, a host that returns only explicitly-set values (@volar/kit), defaults, and pattern normalization.

Closes vuejs/language-tools#6150
Supersedes #126