Add .dockerignore to Python template frontend

[Copilot]

Description

Adds .dockerignore to the Python starter template's frontend directory to exclude node_modules/ from Docker build context, improving build performance and reducing image size.

Fixes #12811

Changes

• Added src/Aspire.ProjectTemplates/templates/aspire-py-starter/13.0/frontend/.dockerignore containing node_modules/ exclusion

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire-docs issue (consider using one of the following templates):
      • New (or update) doc-idea template
      • New breaking-change template
      • New diagnostic template
  • No

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add .dockerignore to Python template (exclude node_modules)</issue_title>
<issue_description>### Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

Currently, the Python starter template at src/Aspire.ProjectTemplates/templates/aspire-py-starter/13.0/frontend does not include a .dockerignore file, which can result in copying unnecessary folders like node_modules into Docker build context. This slows down build times and increases image size.

Describe the solution you'd like

Add a .dockerignore file to src/Aspire.ProjectTemplates/templates/aspire-py-starter/13.0/frontend in the Python template. The file should contain:

node_modules/

This will ensure node_modules is excluded from Docker build context, leading to more efficient builds.

Additional context

Reference for location: frontend folder in repo

No other changes or exclusions are requested at this time.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add .dockerignore to Python template (exclude node_modules) #12811

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 12812

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 12812"

[eerhardt]

/backport to release/13.0

[github-actions]

Started backporting to release/13.0: https://github.com/dotnet/aspire/actions/runs/19178994901

[Copilot]

Pull Request Overview

This PR adds a .dockerignore file to the frontend directory of the aspire-py-starter template to exclude node_modules/ from Docker build contexts.

Key changes:

• Adds a .dockerignore file that excludes node_modules/ from being copied during Docker operations

[eerhardt]

/backport to release/13.0

[github-actions]

Started backporting to release/13.0: https://github.com/dotnet/aspire/actions/runs/19180965693