feat(toolkit-lib): add forceDeployment option to BootstrapOptions (#898)

Fixes #891

This PR adds the `forceDeployment` property to the `BootstrapOptions`
interface to provide parity with the CLI `--force` flag. This allows
programmatic bootstrap operations to force re-bootstrap even when a
bootstrap stack already exists.

## Changes
- Added `forceDeployment?: boolean` property to `BootstrapOptions`
interface
- Added comprehensive test coverage for the new option
- Ensures the force option is properly passed through to SDK calls

## Use Cases
This enables:
- Management account bootstrapping with guaranteed up-to-date bootstrap
stacks
- CI/CD pipelines with clean bootstrap state guarantees  
- Multi-account deployment tools with flexible bootstrap behaviors

---
By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache-2.0 license

Author: mrgrain

packages/@aws-cdk/toolkit-lib/lib/actions/bootstrap/index.ts

@@ -85,6 +85,12 @@ export interface BootstrapOptions {
    * @default true
    */
   readonly terminationProtection?: boolean;
+
+  /**
+   * Whether to force deployment if a bootstrap stack already exists
+   * @default false
+   */
+  readonly forceDeployment?: boolean;
 }
 
 /**

packages/@aws-cdk/toolkit-lib/test/actions/bootstrap.test.ts

@@ -494,6 +494,30 @@ describe('bootstrap', () => {
     await realDispose();
   });
 
+  describe('forceDeployment option', () => {
+    test('accepts forceDeployment option in BootstrapOptions', async () => {
+      // GIVEN
+      const mockStack = createMockStack([
+        { OutputKey: 'BucketName', OutputValue: 'BUCKET_NAME' },
+        { OutputKey: 'BucketDomainName', OutputValue: 'BUCKET_ENDPOINT' },
+        { OutputKey: 'BootstrapVersion', OutputValue: '1' },
+      ]);
+      setupMockCloudFormationClient(mockStack);
+
+      const cx = await builderFixture(toolkit, 'stack-with-asset');
+      const bootstrapEnvs = BootstrapEnvironments.fromCloudAssemblySource(cx);
+
+      // WHEN
+      const result = await toolkit.bootstrap(bootstrapEnvs, {
+        forceDeployment: true,
+      });
+
+      // THEN
+      expectValidBootstrapResult(result);
+      expectSuccessfulBootstrap();
+    });
+  });
+
   describe('error handling', () => {
     test('returns correct BootstrapResult for successful bootstraps', async () => {
     // GIVEN