feat(cdk): add CDK plugin with completion and aliases

Adds a new cdk plugin for the AWS Cloud Development Kit CLI.

- Completion: cached via \cdk --completion zsh\ (same pattern as
  the argocd and helm plugins), stored in \/completions/_cdk
  and refreshed asynchronously on each shell start.
- Aliases: cdkl, cdkls, cdks, cdkd, cdkda, cdkdiff, cdkdes, cdkdesa,
  cdkw, cdkb, cdkdf, cdkdaf, cdkho, cdkdoc, cdkmeta, cdkctx,
  cdkctxr, cdkack.

Closes #11816

plugins/cdk/README.md

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+# CDK plugin
+
+This plugin adds completion support and convenient aliases for the
+[AWS Cloud Development Kit (CDK)](https://docs.aws.amazon.com/cdk/latest/guide/home.html) CLI.
+
+To use it, add `cdk` to the plugins array in your zshrc file:
+
+```zsh
+plugins=(... cdk)
+```
+
+## Requirements
+
+- [Node.js](https://nodejs.org/)
+- [aws-cdk](https://www.npmjs.com/package/aws-cdk) installed globally:
+
+  ```sh
+  npm install -g aws-cdk
+  ```
+
+## Completion
+
+Completions are generated by running `cdk --completion zsh` and cached in
+`$ZSH_CACHE_DIR/completions/_cdk`. The cache is refreshed asynchronously
+each time a new shell session starts.
+
+## Aliases
+
+| Alias      | Command                                       | Description                          |
+|------------|-----------------------------------------------|--------------------------------------|
+| `cdkl`     | `cdk list`                                    | List all stacks in the app           |
+| `cdkls`    | `cdk ls`                                      | Alias for `cdk list`                 |
+| `cdks`     | `cdk synth`                                   | Synthesize CloudFormation template   |
+| `cdkd`     | `cdk deploy`                                  | Deploy a stack                       |
+| `cdkda`    | `cdk deploy --all`                            | Deploy all stacks                    |
+| `cdkdiff`  | `cdk diff`                                    | Show diff against deployed stack     |
+| `cdkdes`   | `cdk destroy`                                 | Destroy a stack                      |
+| `cdkdesa`  | `cdk destroy --all`                           | Destroy all stacks                   |
+| `cdkw`     | `cdk watch`                                   | Watch for changes and auto-deploy    |
+| `cdkb`     | `cdk bootstrap`                               | Bootstrap CDK into an AWS account    |
+| `cdkdf`    | `cdk deploy --require-approval never`         | Deploy skipping approval prompts     |
+| `cdkdaf`   | `cdk deploy --all --require-approval never`   | Deploy all, skip approval prompts    |
+| `cdkho`    | `cdk deploy --hotswap`                        | Hotswap deploy (Lambda/ECS/etc.)     |
+| `cdkdoc`   | `cdk doctor`                                  | Check CDK environment setup          |
+| `cdkmeta`  | `cdk metadata`                                | Display stack metadata               |
+| `cdkctx`   | `cdk context`                                 | View cached context values           |
+| `cdkctxr`  | `cdk context --reset`                         | Reset all cached context values      |
+| `cdkack`   | `cdk acknowledge`                             | Acknowledge a CDK notice             |

plugins/cdk/cdk.plugin.zsh

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+# Autocompletion for the AWS CDK CLI.
+#
+# AWS CDK supports generating its own zsh completion script via
+# `cdk --completion`. This plugin caches that output and refreshes
+# it asynchronously on each shell start, following the same pattern
+# used by the argocd and helm plugins.
+
+if (( ! $+commands[cdk] )); then
+  return
+fi
+
+# If the completion file doesn't exist yet, we need to autoload it and
+# bind it to `cdk`. Otherwise, compinit will have already done that.
+if [[ ! -f "$ZSH_CACHE_DIR/completions/_cdk" ]]; then
+  typeset -g -A _comps
+  autoload -Uz _cdk
+  _comps[cdk]=_cdk
+fi
+
+cdk --completion zsh >| "$ZSH_CACHE_DIR/completions/_cdk" &|
+
+# ── Aliases ──────────────────────────────────────────────────────────────────
+
+# Core workflow
+alias cdkl='cdk list'
+alias cdkls='cdk ls'
+alias cdks='cdk synth'
+alias cdkd='cdk deploy'
+alias cdkda='cdk deploy --all'
+alias cdkdiff='cdk diff'
+alias cdkdes='cdk destroy'
+alias cdkdesa='cdk destroy --all'
+alias cdkw='cdk watch'
+alias cdkb='cdk bootstrap'
+
+# Faster deploys
+alias cdkdf='cdk deploy --require-approval never'
+alias cdkdaf='cdk deploy --all --require-approval never'
+alias cdkho='cdk deploy --hotswap'
+
+# Metadata / diagnostics
+alias cdkdoc='cdk doctor'
+alias cdkmeta='cdk metadata'
+alias cdkctx='cdk context'
+alias cdkctxr='cdk context --reset'
+alias cdkack='cdk acknowledge'