Improve devcontainer startup times

[trxcllnt]

This PR builds and publishes devcontainers to ghcr.io and uses the new images to improve CI and local devcontainer startup times.

In rapidsai/devcontainers, devcontainer startup times went from 3m28s to 34s.

Contributes to rapidsai/build-planning#280.

[coderabbitai]

📝 Walkthrough

Summary by CodeRabbit

• Chores
  • Optimized Docker build performance for development containers by enabling build cache reuse.
  • Added automated publishing of development container images for CUDA 12.9 and 13.2 versions.

Walkthrough

This PR updates devcontainer configurations to use Docker build caching and adds a GitHub Actions workflow job to automatically build and publish devcontainer images for CUDA 12.9 and 13.2 variants.

Changes

DevContainer Build Cache and CI Integration

Layer / File(s)	Summary
DevContainer build cache sources .devcontainer/cuda12.9-conda/devcontainer.json, .devcontainer/cuda12.9-pip/devcontainer.json, .devcontainer/cuda13.2-conda/devcontainer.json, .devcontainer/cuda13.2-pip/devcontainer.json	Each devcontainer configuration adds a build.cacheFrom array referencing a pre-built registry image (ghcr.io/rapidsai/nvforest/devcontainer:26.08-cuda*-*) to enable Docker layer caching across local and CI builds.
CI workflow devcontainer publishing job .github/workflows/build.yaml	A new devcontainers job is appended to the build workflow, calling the shared reusable workflow build-devcontainers.yaml with push: true and targeting CUDA versions 12.9 and 13.2; the job inherits secrets and requests packages: write permissions.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• rapidsai/nvforest#82: Introduced devcontainer configurations for CUDA variants; this PR adds build caching and CI automation to those configurations.

Suggested reviewers

• bdice
• jameslamb

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main objective of the changeset, which is to improve devcontainer startup times through building and publishing cached images.
Description check	✅ Passed	The description is directly related to the changeset, explaining that devcontainers are being built and published to ghcr.io, and citing measurable improvements in startup times.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In @.github/workflows/build.yaml:
- Around line 189-197: The devcontainers job (named "devcontainers" with push:
true) must be gated on successful wheel publish jobs; add a needs: key to the
devcontainers job listing the wheel build/publish job IDs (e.g., the job names
that build and publish wheels such as build-wheels or publish-wheels) so the
devcontainers job only runs after those wheel jobs succeed, keeping the existing
permissions and with: push: true unchanged.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: d56a11a1-762d-41df-bf71-f968cea6c461

📥 Commits

Reviewing files that changed from the base of the PR and between 8bb23ee and 09b493b.

📒 Files selected for processing (5)

• .devcontainer/cuda12.9-conda/devcontainer.json
• .devcontainer/cuda12.9-pip/devcontainer.json
• .devcontainer/cuda13.2-conda/devcontainer.json
• .devcontainer/cuda13.2-pip/devcontainer.json
• .github/workflows/build.yaml

[trxcllnt]

/merge