Implement @ngrx/eslint-plugin for NgRx Signals and Component Store linting

Description

Add and configure @ngrx/eslint-plugin in the core-web Nx monorepo to enforce NgRx best practices for the packages currently in use.

The monorepo already uses NgRx Signals, Component Store, and Operators (@ngrx/signals, @ngrx/component-store, @ngrx/operators at 21.1.1) across multiple stores and features (e.g. edit-content, edit-ema, global-store, image-editor, portlets). ESLint is configured with flat config (eslint.config.mjs) at the workspace root and per project, but there is no NgRx-specific lint coverage today.

Implementation should follow the official NgRx ESLint plugin installation guide: https://ngrx.io/guide/eslint-plugin/install

Scope

Implementation notes

• Prefer ng add @ngrx/eslint-plugin — the schematic supports ESLint 9 flat config (eslint.config.mjs).
• Peer dependency typescript-eslint is already present in the workspace.
• Apply NgRx rules to TypeScript files that use NgRx patterns (stores, features, component-store), not unrelated SDK or utility libraries.

Acceptance Criteria

• @ngrx/eslint-plugin is added as a devDependency at a version compatible with the existing @ngrx/* packages (21.1.1)
• core-web/eslint.config.mjs is updated via ng add @ngrx/eslint-plugin with NgRx rule configs for signals, component-store, and operators only (not store or effects)
• NgRx ESLint rules apply to TypeScript files that use NgRx (stores, signal stores, component stores, features) without breaking lint for unrelated projects
• pnpm run lint:dotcms completes with zero NgRx ESLint violations across the workspace
• All pre-existing NgRx rule violations in affected files are fixed in the same change (no blanket rule downgrades to warn/off unless individually justified in code review)
• CI lint checks for core-web pass after the change

Additional Context

• Reference: https://ngrx.io/guide/eslint-plugin/install
• Current ESLint setup: Flat config at core-web/eslint.config.mjs with @nx/eslint-plugin, TypeScript, import, and stylistic rules
• NgRx usage: Widespread @ngrx/signals (signalStore, features) and @ngrx/component-store across portlets and shared libs; see core-web/CLAUDE.md ("Use NgRx signals for state management")
• Version alignment: Keep @ngrx/eslint-plugin on the same major/minor line as @ngrx/signals / @ngrx/component-store / @ngrx/operators

Start with core-web/eslint.config.mjs, the existing flat ESLint configuration, and the official @ngrx/eslint-plugin installation guide. Run ng add @ngrx/eslint-plugin, then run pnpm run lint:dotcms and inspect NgRx-using stores, features, and component-store files for violations. Done means the signals, component-store, and operators rules are configured, violations are fixed, and core-web CI lint passes without affecting unrelated projects.