feat(i18n): full app + docs localization (de/en)

- translate remaining pages/components (admin, analytics, redundancy,
  trash, compare, browse, watchlist, admin tools tab, category combobox,
  theme toggle, tool preview card, tool-new/edit) to t() calls
- locales: 453 keys each, parity verified
- docs: bilingual handbook + release notes via *.en.md variants,
  language-aware docs.tsx (markdown paths, nav titles, search index),
  LanguageSwitcher in docs header
- generate-docs: emit per-locale handbook/release/search output,
  localized index.json fields (fileEn/titleEn), en-aware snapshots

docs/releases/v0.8.1.en.md

@@ -0,0 +1,47 @@
+# v0.8.1 — Release Notes
+
+**Date:** 2026-08-03 · **Tag:** [`v0.8.1`](https://git.kubebase.de/admin/tool-evaluator/releases/tag/v0.8.1)
+
+## New features
+
+- **Standalone docs page**: The documentation is now available as its own,
+  mkdocs-like page at `toolr.kubebase.de/docs` — without the app shell
+  (own header with repo link, version dropdown, search, theme toggle
+  and link back to the app).
+- **Navigation renamed**: The sidebar entry is now called **"Help"**
+  and leads to the standalone docs.
+- **User guide completely revised**: 17 manual pages with
+  step-by-step instructions for all features (finding tools, creating a
+  tool, evaluating, watchlist, comparing, costs, analytics, plans,
+  administration, redundancy, trash, keyboard shortcuts, data model).
+
+## Fixes & improvements
+
+- Reference links are now case-insensitive
+  (schema/endpoint slugs such as `toolinput` and `ToolInput` both work).
+- Manual links to endpoint anchors corrected (PascalCase operation IDs).
+- Outdated, broken manual links (`vergleichen`, `watchlist` …) replaced.
+- Documentation table headers and notice texts in the docs page
+  internationalized via i18n (de/en).
+
+## API changes
+
+- No changes to the API.
+
+## Operations / upgrade
+
+- **Env vars:** unchanged.
+- **Migration:** none.
+- **Breaking changes:** none. The docs page is reachable under `/docs` as
+  before; only the presentation is now standalone.
+
+## Known limitations
+
+- Manual & reference apply to the current version; older versions show
+  their release notes and a reference snapshot, if generated at release time
+  (`node scripts/src/generate-docs.mjs --snapshot vX.Y.Z`).
+
+## Links
+
+- Commit: [`fdf2d74`](https://git.kubebase.de/admin/tool-evaluator/commit/fdf2d74)
+- Tag: [`v0.8.1`](https://git.kubebase.de/admin/tool-evaluator/releases/tag/v0.8.1)