Add composeNav helper (todo §1); merge plugin nav fragments + central override (rename/group/order/hide), role-filter to a nav-tree model

todo.md

@@ -34,7 +34,7 @@ everything via Docker.
 - [x] Pagination partial — rows-per-page + page numbers, query-param driven. → `views/partials/pagination.ejs`: data-driven, zero-JS. `summary {from,to,total}`, rows-per-page GET `<form>` (select + submit, `hidden[]` carries list state), `pages: {label,href?,current?,ellipsis?}[]` (links; current/ellipsis inert), `prev`/`next` (href ⇒ link, omit ⇒ disabled). Reuses the mockup's `.pager` CSS, no changes. `pagination.test.ts` covers the matrix + value reflection + empty defaults.
 - [x] Form-field partials (input/label/hint/error) + auth-card partial. → `views/partials/field.ejs`: data-driven `.field` — label (+ inline `link`/`Optional`), optional icon input (`has-ico`), `hint`, server-driven `error` (string | {text} | {html}) wiring `aria-invalid` + `aria-describedby`; added one CSS rule `.field.has-error .field-error{display:flex}` so a rendered field shows its own error. `views/partials/auth-card.ejs`: the `<form class="auth-card">` shell — head (back/title/sub), optional `sso` providers (text logo or icon, link or button) + divider, `body` slot (fields + submit), `alt` footer. `field.test.ts`/`auth-card.test.ts` cover the matrix + escaping + defaults.
 - [x] Menu/popover + theme-switch partials (pure CSS `details`/`summary`). → `views/partials/menu.ejs`: data-driven `<details>` popover — `trigger` (icon/text/raw-html, `class:""` ⇒ bare kebab), `align`/`up` positioning, `width`; `items` = head · sep · link/button (icon, danger) · check-`group` (the columns/“more filters” menus filter-bar deferred here). `views/partials/theme-switch.ejs`: Light/Auto/Dark radiogroup with the fixed `theme-light/auto/dark` ids `styles.css` keys its `:has()` swaps off. Added `.menu-pop.up` (replaces the mockup's inline up-positioning); `shell.ejs` now reuses both partials. `menu.test.ts`/`theme-switch.test.ts` cover the matrix + escaping + defaults.
-- [ ] Helper `composeNav(fragments, override, roles)` → merged, permission-filtered tree.
+- [x] Helper `composeNav(fragments, override, roles)` → merged, permission-filtered tree. → `src/nav.ts`: pure, I/O-free. Flattens plugin fragments, applies the central override (rename → group → order → hide, all keyed by node `id`), then role-filters — a node shows iff it has no `permission` or `roles` includes it; a gated header drops its whole subtree, an emptied pure header is dropped. Emits clean nodes (no `id`/`permission`, absent fields omitted) ready for `nav-tree.ejs`. Filter runs last so everything above is per-deployment. `NavNode`/`NavOverride`/`NavGroupSpec` types exported; `nav.test.ts` covers merge/filter/empties/override matrix.
 - [ ] Helper `parseListQuery(url)` → `{ q, filters, sort, page, pageSize }`.
 - [ ] Helper `paginate(total, page, pageSize)` → page model.
 - [ ] Replace placeholder `index` with the app-shell dashboard.