Land the I18N adapter boundary before bumping ngx-translate to v18

[opensource-joe]

Split out of #442. #207 bumps @ngx-translate/core to v18. That is a major, and today it would touch 317 files. This is the work that makes it touch three.

Drop a dead dependency first. @ngx-translate/http-loader is still in package.json and nothing imports it. #437 replaced it; only a comment at app.config.ts:132 remains.

The boundary exists on paper only. ADR-0003 puts ngx-translate behind the I18N token, but 317 files import @ngx-translate/core directly and only 3 are in core/adapters/. Lint already forbids it; the other 312 sit in eslint-suppressions.json. Note the templates are inline in the .ts files.

Order:

1. | translate to | appTranslate, dropping TranslateModule from each component's imports. 2,860 sites, 604 already done. Not a good first issue, unlike Consolidate the open Angular dependency bumps into one lockstep PR #442.
2. Move the 40 TranslateService injections onto the I18N token.
3. Then build(deps): bump @ngx-translate/core from 17.0.0 to 18.0.0 #207, confined to ngx-translate-i18n.adapter.ts, deployment-translate.loader.ts and app.config.ts.

Acceptance: http-loader gone, no @ngx-translate/core import outside the adapter, no no-restricted-imports suppressions left for it, and lint, both unit suites and the mocked and mobile Playwright projects green.

Counts measured on main at b1d9280. Background: DOCS/adr/0003-adapter-boundary.md.