Enable Glint by default for both JS and TS apps

[wagenet]

Summary

Implements RFC #976: Enable Glint by Default for the app blueprint. Glint v2 is now installed and configured for both TS and JS apps.

The blueprint already shipped Glint v2 packages — this PR moves them out of the `<% if (typescript) %>` blocks so JS apps benefit from editor tooling out of the box.

• TS path: `tsconfig.json` and the existing `lint:types: ember-tsc --noEmit` script — unchanged.
• JS path: a new `jsconfig.json` (not `tsconfig.json`) that signals "IDE tooling only, no CLI type-check." Glint deps are installed for editor support; no `lint:types` script is added.
• `@glint/ember-tsc`, `@glint/template`, `@glint/tsserver-plugin`, `@ember/app-tsconfig`, and `typescript` move out of the TS-only conditional in `package.json`.
• The previous `!file.startsWith('types/')` filter for JS apps is dropped — both jsconfig.json and tsconfig.json reference `types/`, and the dir doesn't currently contain blueprint-shipped files.
• `index.js` filters `jsconfig.json` out of TS apps, symmetric to the existing `tsconfig.json` filter for JS apps.

Related

• RFC: Enable Glint by Default emberjs/rfcs#976
• Companion change in upstream ember-cli (legacy app-blueprint inside the monorepo): Switch app and addon blueprints to Glint v2 ember-cli#11015
• Sibling addon-blueprint PR: ember-cli/ember-addon-blueprint (will link)
• Docs: typescript: document Glint as a default ember-learn/guides-source#2211
• Announcement post: Add Glint-by-default announcement post ember-learn/ember-blog#1373

Test plan

• Generate a JS app: `ember new my-app` against this blueprint. Confirm `jsconfig.json` present, no `tsconfig.json`, Glint v2 packages installed.
• Generate a TS app: `ember new my-app --typescript`. Confirm `tsconfig.json` present, no `jsconfig.json`, `lint:types: ember-tsc --noEmit` works.
• CI: existing blueprint tests pass.

Note on archived predecessor

The earlier `embroider-build/app-blueprint` is archived; this PR is the same set of changes adapted for the new structure here.

🤖 Generated with Claude Code

[mansona]

why are we doing this? 🤔 recent discussions in the tooling team meetings suggested that it was a good idea to make glint work out of the box without needing any typescript or jsconfig stuff, and thankfully that has all been done upstream 🎉

is there a real reason why you think that we should make this change? or is it just following what the original RFC said? if it's the latter then that might prompt a potential update to the RFC saying that we intend to make it work out of the box (in things like VS code) without any code changes in apps or blueprints. What do you think?

[NullVoxPopuli]

since we figured out how to get glint in the ember extension pack and working on js projects, I don't think we need this 🎉 thanks for helping us explore this!