feat(design-system): add reusable Input primitive

ControlValueAccessor-based, standalone, OnPush. Sizes sm/md/lg, states default/error/success.
Colors/radius/spacing/transitions consumed via existing tenant CSS vars (--border-color,
--primary-color, --error-color, --success-color, etc) with fallbacks - compatible with
bootstrap JSON theming and Project Editor live preview.

src/app/shared/ui/input/input.component.ts

@@ -0,0 +1,64 @@
+import { ChangeDetectionStrategy, Component, forwardRef, input } from '@angular/core';
+import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';
+
+export type InputSize = 'sm' | 'md' | 'lg';
+export type InputState = 'default' | 'error' | 'success';
+
+@Component({
+  selector: 'app-input',
+  standalone: true,
+  templateUrl: './input.component.html',
+  styleUrl: './input.component.scss',
+  changeDetection: ChangeDetectionStrategy.OnPush,
+  providers: [
+    {
+      provide: NG_VALUE_ACCESSOR,
+      useExisting: forwardRef(() => InputComponent),
+      multi: true
+    }
+  ],
+  host: {
+    '[class.app-input-host--full-width]': 'fullWidth()'
+  }
+})
+export class InputComponent implements ControlValueAccessor {
+  readonly type = input<'text' | 'email' | 'password' | 'number' | 'search' | 'tel' | 'url'>('text');
+  readonly size = input<InputSize>('md');
+  readonly state = input<InputState>('default');
+  readonly placeholder = input('');
+  readonly disabled = input(false);
+  readonly fullWidth = input(false);
+  readonly ariaLabel = input<string | null>(null);
+
+  protected value: string | number = '';
+  protected isDisabled = false;
+
+  private onChange: (value: string | number) => void = () => {};
+  private onTouched: () => void = () => {};
+
+  writeValue(value: string | number): void {
+    this.value = value ?? '';
+  }
+
+  registerOnChange(fn: (value: string | number) => void): void {
+    this.onChange = fn;
+  }
+
+  registerOnTouched(fn: () => void): void {
+    this.onTouched = fn;
+  }
+
+  setDisabledState(isDisabled: boolean): void {
+    this.isDisabled = isDisabled;
+  }
+
+  protected handleInput(event: Event): void {
+    const target = event.target as HTMLInputElement;
+    this.value = target.value;
+    this.onChange(this.value);
+  }
+
+  protected handleBlur(): void {
+    this.onTouched();
+  }
+}