fix: apply Angular and Ionic audit improvements

docs/code-style-audit.md

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+# Angular and Ionic code audit
+
+Reviewed on 2026-11-04 against the installed Angular 22 and Ionic 9 packages.
+Scope: application components, templates, styles, services, localization,
+bootstrap, routes, TypeScript configuration, and lint rules.
+
+## Corrections
+
+- Moved court and queue state changes from page orchestration into
+  `CourtRotationService`. Moves and rotations now use transactions, await writes,
+  check persisted court occupancy, and reject stale confirmations. A failed write
+  rolls back the entire operation.
+- Fixed rotation without confirmation when service judges are disabled. The lone
+  umpire returns to the umpire queue.
+- Moved court-count and service-judge cleanup into `SettingsService` transactions.
+  Court counts must be positive safe integers. Court count changes commit after
+  the input is confirmed rather than deleting assignments during each keystroke.
+- Made roster deletion remove dependent duty records and normalize remaining
+  queue positions in the same transaction. Clearing the roster clears duty too.
+- Made queue insertion/reordering and deletion/renumbering atomic. Queue heads
+  use the lowest numeric order, including when the first order is greater than one.
+- Replaced method-created `toSignal()` court queries with `computed()` lookups
+  derived from existing service signals. Callers no longer need an injection
+  context or create a new database subscription for every lookup.
+- Kept defensive copies of caller-owned records before Dexie inserts, so generated
+  IDs do not mutate form or caller state. Removed unnecessary entity casts.
+- Made roster saves finish before modal dismissal. The form prevents duplicate
+  saves, rejects blank names, trims names and country, and preserves the draft
+  with a translated error alert when saving fails. Modal presentation uses its
+  Angular view reference instead of a global trigger ID.
+- Replaced the court loop's array-constructor migration expression with the
+  existing computed court indexes and stable court-number tracking.
+- Corrected Ionic grid boolean bindings, removed redundant literal property
+  bindings and an empty disabled binding, and applied the empty-court drag
+  predicate consistently to both roles.
+- Localized the remaining hardcoded roster heading, added names for icon-only
+  actions, allowed browser zoom, and synchronized the document language with
+  the selected UI language.
+- Exposed language state as a readonly signal and rejected inherited object keys
+  such as `toString` as saved language values.
+- Replaced alert styles coupled to generated Ionic classes with the public host
+  class and CSS variables, with a viewport-aware minimum width.
+- Added bootstrap error handling and moved the desktop platform lookup inside
+  the updater's error boundary.
+- Removed unused dependencies, imports, pipe arguments, and non-null assertions;
+  added `readonly` where appropriate and typed Ionic events and CDK drag data.
+- Enabled lint rules for unused variables and explicit `any`. Removed the blanket
+  suppression of optional-chain and nullish-coalescing compiler diagnostics.
+- Formatted changed files with the repository Prettier configuration and updated
+  the architecture documentation.
+
+## Conventions retained
+
+- Ionic 9 exports standalone components from `@ionic/angular`; no import-path
+  migration is needed. The installed package does not export the old
+  `@ionic/angular/standalone` entry point.
+- Eager change detection remains explicit on the root and Ionic routed components.
+  Ionic outlet ancestors must continue checking pages that use plain-field form
+  state. See [Ionic page lifecycle](https://ionicframework.com/docs/angular/lifecycle).
+- Existing standalone components, lazy routes, `inject()`, strict typing, reactive
+  service signals, and computed page state already follow the project's approach.
+  See [Ionic standalone build options](https://ionicframework.com/docs/angular/build-options)
+  and [Angular component guidance](https://github.com/angular/angular/blob/main/packages/core/resources/best-practices.md).
+- The translation and full-name pipes remain impure: their output depends on a
+  language signal in addition to the explicit pipe arguments.
+- Template-driven forms remain appropriate for the small roster form. This audit
+  does not require a form-framework migration.
+- No database schema, release versions, dependencies, or tournament rules changed.
+
+## Validation
+
+Final checks, using Node `lts/jod`:
+
+- `npm run lint` — passed.
+- `npm run build` — passed, including strict template checking with diagnostic
+  suppressions removed.
+- `CHROME_BIN=/snap/bin/chromium npm test -- --watch=false --browsers=ChromeHeadless`
+  — all 102 tests passed. Karma and Chromium ran outside the sandbox because the
+  sandbox cannot bind Karma's server port.
+- Focused roster tests using `--include=src/app/tab2/tab2.page.spec.ts` — all four
+  passed before the final full-suite run.
+- Prettier on touched files and `git diff --check` — passed.
+
+Regression coverage includes concurrent assignment attempts, failed rotation
+rollback, stale confirmations, FIFO ordering with gaps, state exclusivity,
+settings cleanup, cascade deletion, readonly language behavior, name localization,
+and roster save failure and duplicate-submit behavior.
+
+Desktop installation, updater downloads, native platform builds, and manual
+end-to-end drag interaction were not exercised by this frontend audit.
+The existing Karma builder and Zone.js/Jasmine integration emit upstream
+deprecation messages; migrating the runner or dependency versions is separate
+from these application fixes.