Adopt latest glint setup (ember-tsc) and pin TypeScript to 6.x

[Copilot]

Migrates the workspace from the deprecated glint 1.4 environment-based setup to the current @glint/ember-tsc setup used by the ember-cli/ember-addon-blueprint, and pins TypeScript to ~6.0.0 (CI matrix reduced to 6.x only).

Glint

• Removed @glint/core, @glint/environment-ember-loose, @glint/environment-ember-template-imports from every package.
• Added @glint/ember-tsc (^1.0.3) and @glint/tsserver-plugin (^2.0.0); bumped @glint/template to ^1.6.1.
• lint:types now runs ember-tsc --noEmit (and test-app's typecheck script runs ember-tsc --version).

tsconfig

• Dropped the "glint": { "environment": [...] } block — no longer needed.
• Added "types": ["ember-source/types", "@glint/ember-tsc/types"] to every compilerOptions.
• Replaced @tsconfig/ember with @ember/library-tsconfig (addons) and @ember/app-tsconfig (apps).
• Removed every @types/ember* / @types/ember-data* devDep; those types now ship with ember-source.

Template registries

Registry declarations moved from @glint/environment-ember-loose/registry to @glint/template/registry in all three addon unpublished-development-types/index.d.ts files, test-app/types/global.d.ts, docs-app/types/glint-registry.d.ts, and the TypeScript docs page:

import type HeadlessFormRegistry from 'ember-headless-form/template-registry';

declare module '@glint/template/registry' {
  export default interface Registry extends HeadlessFormRegistry {
    // your app's own entries here...
  }
}

TypeScript 6

• Every package's typescript devDep pinned to ~6.0.0.
• CI TS matrix reduced from 5.4 / 5.5 / 5.6 / 5.7 to just typescript@6.0.

pnpm

• Moved peerDependencyRules from package.json into pnpm-workspace.yaml; pnpm 10 no longer reads them from package.json, so the existing rules were silently inert.
• Added ignoreMissing: [@glint/environment-ember-loose] (still declared by some transitive deps such as @crowdstrike/ember-oss-docs) and allowedVersions: { typescript: '6' } (for deps like rollup-plugin-ts that still declare ^5).

[NullVoxPopuli]

@copilot we should still test typescript 5.9 as well

[Copilot]

Added typescript@5.9 back to the matrix alongside typescript@6.0 in 0680c9a.

[NullVoxPopuli]

@copilot you need to deal with a TypeScript deprecation that printed in the lint job.

[Copilot]

@copilot you need to deal with a TypeScript deprecation that printed in the lint job.

The deprecation was Option 'baseUrl' is deprecated and will stop functioning in TypeScript 7.0, emitted by rollup-plugin-ts (which injects a default baseUrl internally). Added "ignoreDeprecations": "6.0" to every workspace tsconfig.json in 8205158; verified locally that packages/changeset and packages/yup now build cleanly.