Added CLAUDE.md and development rules for Claude Code.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.claude/rules/frontend.md

@@ -0,0 +1,39 @@
+---
+paths:
+  - "src/pages/**"
+  - "src/components/**"
+  - "src/locales/**"
+  - "src/app.rs"
+  - "src/validator.rs"
+  - "style/**"
+---
+
+# Frontend rules
+
+## Components
+
+- Leptos 0.6 API only. Components are `#[component]` functions returning `impl IntoView`, one page or dialog per file in `src/pages/`; reusable building blocks go to `src/components/`. Register new files in the respective `mod.rs` (`pub mod` only if used from `app.rs`).
+- This code runs on the server (SSR) and in the browser (hydration). Browser-only APIs (`window()`, `web_sys`) must not run during SSR — keep them in event handlers/effects or behind `#[cfg(not(feature = "ssr"))]`. Markup must render the same on both sides or hydration breaks.
+- A new admin page needs a `<Route path="admin/..."/>` in `src/app.rs` wrapped in `<AdminPortal>`, and a menu entry in `src/components/admin_portal.rs`. Paths starting with `/admin` are login-protected by the middleware; data access is still guarded by `perm_check!` in the server fn.
+
+## Data loading and forms
+
+- Load data with `create_blocking_resource` / `create_resource` calling the server fn, rendered inside `<Transition fallback=...>` with `{trl("Loading...")}`. Use a dialog's `opener.visible()` as the resource source so lists reload after the dialog closes (see `src/pages/users.rs`).
+- Handle all three outcomes of a server call: `Err(e)`, `Ok(ApiResponse::Error(msg))`, `Ok(ApiResponse::Data(d))`.
+- Edit/create dialogs: `DialogOpener::new()` in the parent, `create_server_action::<ServerFnStruct>()` in the dialog, wrapped in `<DataForm opener=.. action=.. title="..">`. It supplies the modal, Save/Close buttons, client validation and server error display. Confirmations use `<QuestionDialog>`.
+- Form field names follow the server fn argument: `name="company[name]"`. Pass the id as a hidden input. Fill inputs with `prop:value={move || signal.get().field}`.
+- `DataForm`/`ModalDialog` take `title` as an untranslated English key (`&'static str`); they translate it themselves.
+
+## Translations
+
+- Every user-visible string goes through `trl("English text")`; never hard-code Czech (or any text) in a view. The English text is the key and the fallback.
+- When you add or change a key, add the Czech translation to the `cs` map in `src/locales/catalogues.rs`. This includes validation `message`s and `ApiResponse::Error` strings from the backend.
+- `trl()` returns a closure — use it directly as `{trl("...")}` or attribute value; call it (`trl("...")()`) when a `String` is needed.
+- Dates shown to users go through `loc_date()`, weekday names through `show_day()`.
+
+## Styling
+
+- UI is the Bootstrap-based admin template in `assets/vendor/` plus Boxicons (`<i class="bx bx-...">`). Reuse its classes (`card`, `table`, `btn btn-primary`, `form-control`, `row`/`col`) before writing CSS.
+- Custom styles go to `style/main.scss`. Never edit `assets/vendor/`.
+- The public page banner style is `assets/data/banner.css`, rewritten at runtime by the appearance upload (`/*bg-img*/` marker) — keep that marker / the `background-image: url('...')` form intact.
+- Stylesheets and meta tags are declared in `src/components/header.rs`.