Finalize Context Importer naming and review Extensions page UI/UX
## Description
Follow-up to:
#3586275+s
Required for:
#3586282+s
### Summary
[#3586275](https://www.drupal.org/project/ai_context/issues/3586275) introduced the `ai_context_document_loader` submodule and a reworked **Settings → Extensions** page (`/admin/config/ai/context/settings/extensions`).
This issue locked in final naming and validated the Extensions page design before the submodule stabilization follow-up (experimental → stable) (#3586282).
UX review with Aidan approved the Feature column and requested only naming tweaks (implemented in !188). No other Extensions page layout or interaction changes were requested.
[]
### Background
Extensions page structure (kept):
- **General** table — optional extensions (Diff, Dynamic Entity Reference)
- **Importers** section — intro paragraph + table for import-related modules
- Four columns: **Feature**, **Description**, **Module**, **Status**
- Submodule row:
- Feature: `Markdown file importer`
- Module: `Document Loader: Context File Importer (submodule)` → links to Extend with `?filter=ai_context_document_loader`
- Importers intro links to Document Loader project page; description cells include “Requires …” lines with inline links
### Naming decisions
| Area | Final decision |
|------|----------------|
| Submodule display name | `Document Loader: Context File Importer` |
| Machine name | Keep `ai_context_document_loader` |
| Feature label | Keep `Markdown file importer` |
| URL importer feature | Keep `Markdown URL importer` |
| Docs / README / Extend page | Use **Context File Importer** consistently |
| Internal method names | Keep (e.g. `buildMarkdownImporterDescription()`); no rename required for this issue |
| General Diff feature | `Context revision comparison` (was “Context item revision comparison”) |
### UI/UX decisions
Reviewed with Aidan. Only naming changes were requested; everything else accepted as-is.
#### Information architecture
- [x] **General** vs **Importers** — keep
- [x] **Feature** vs **Module** — keep (Feature column liked in review)
- [x] `(submodule)` suffix — keep
- [x] Required vs optional dependencies — keep current “Requires …” copy; no extra visual treatment
#### Copy and links
- [x] Importers intro text — keep
- [x] Description “Requires Document Loader and AI File to Text…” — keep
- [x] “Context revision comparison” rename — keep (applied)
#### Visual / interaction
- [x] Intro vs table link underline styling — accept Gin/theme default; no change
- [x] Fixed table column widths — keep for now
- [x] Extend `?filter=` prefill — keep
- [x] Submodule / Extend links open in new tab — keep
#### Accessibility
- [x] Table headers, link purpose, and status labels — accepted with current markup for this issue
- [x] Contrast / focus for requirement links — no change requested; follow up separately if needed
### Tasks
- [x] UX review with maintainers
- [x] Document decisions (this description)
- [x] Apply agreed naming updates across:
- `ai_context_document_loader.info.yml`
- `AiContextExtensionsController.php`
- docs (`importers.md`, `index.md`, `README.md`, submodule README)
- functional/unit tests
- [x] No further UI/CSS/link-behavior changes beyond naming
- [x] Update `AiContextAdminSettingsTest` and `AiContextExtensionsControllerTest` for final strings/structure
### Acceptance criteria
- [x] Naming is finalized and consistent across UI, docs, and tests
- [x] Extensions page IA, copy, and link behavior reviewed and signed off
- [x] No remaining “Markdown Importer” or bare “Context Importer” user-facing references
- [x] Tests reflect final naming and page structure
### Out of scope
- Removing `lifecycle: experimental` (stabilization follow-up)
- Canvas patch upstream work ([#3575644](https://git.drupalcode.org/project/canvas/-/work_items/3575644))
- End-to-end import functional tests (stabilization follow-up) (#3586282)
### Related
- Parent: [#3586275](https://www.drupal.org/project/ai_context/issues/3586275)
- Blocks: stabilization follow-up (experimental → stable) (#3586282)
- MR: !188
- Page: `/admin/config/ai/context/settings/extensions`
## AI usage
- [x] AI assisted issue
issue