Integrate ScriptExecutor into HooksRunner

Part of #7435 — Multi-Language Hook Support

User Story

As a template consumer, I want Python hooks defined in azure.yaml to execute automatically during azd up/azd deploy alongside existing shell hooks so the deployment lifecycle works end-to-end.

Solution Approach

Modify pkg/ext/hooks_runner.go:

1. Add import for pkg/tools/language.

2. Add GetScriptExecutor(hookConfig *HookConfig) (language.ScriptExecutor, error) method:

   • Resolve executor via language.GetExecutor(hookConfig.ScriptLanguage(), h.commandRunner, h.console, h.cwd).

3. Update execHook() — branch on hookConfig.IsLanguageHook():

   if hookConfig.IsLanguageHook() {
       executor, err := h.GetScriptExecutor(hookConfig)
       // ...
       if err := executor.Prepare(ctx, hookConfig.path); err != nil { ... }
       res, err := executor.Execute(ctx, hookConfig.path, *options)
       // ... shared post-execution logic ...
   } else {
       // existing shell hook path — unchanged
   }

4. Extract shared post-execution logic (ContinueOnError, output previewer, cleanup) into helper to avoid duplication.

5. Thread environment variables via ExecOptions.Env or executor constructor.

Modify pkg/ext/hooks_runner_test.go:

1. Python hook full pipeline (mock CommandRunner expects: version check → venv → pip → execute)
2. Shell hook unchanged (.sh does NOT trigger language path)
3. ContinueOnError with failing Python hook
4. Interactive mode flag passthrough

Follow existing test pattern: mocks.NewMockContext, mockenv.MockEnvManager, mockContext.CommandRunner.When(...).RespondFn(...).

Files: pkg/ext/hooks_runner.go (MODIFY), pkg/ext/hooks_runner_test.go (MODIFY)

Acceptance Criteria

• Python .py hooks execute through ScriptExecutor path automatically
• Shell .sh/.ps1 hooks execute through existing Script path (no regression)
• Inline shell hooks completely unaffected
• Error messages clearly indicate which hook and language failed
• ContinueOnError and Interactive flags work for language hooks
• Environment variables passed to language hooks

References

• Refs: Contributes to A standard or better way to populate local environments with azd env variables #4384; Related to Add a first-class command to run a process with the current azd environment loaded #7423
• Contributes to: Multi-Language Hook Support: Python, JavaScript, TypeScript, .NET #7435