Add pkg/vmcp/cli/init.go for vMCP config scaffolding

[yrobla]

Summary

Implement Init(ctx, InitConfig) which discovers running workloads in a named ToolHive group via an injected Discoverer, renders a commented starter YAML config pre-populated with one backend entry per accessible workload, and writes the result to a file (0o600) or an io.Writer.

Workloads returning nil from GetWorkloadAsVMCPBackend are skipped with a debug log. Empty groups produce a valid YAML skeleton with backends: [].

Includes unit tests covering writer output, file output, nil-backend skipping, empty groups, discovery errors, YAML validity (loader + validator), file permissions, and input validation edge cases.

Fixes #4882

Type of change

• Bug fix
• New feature
• Refactoring (no behavior change)
• Dependency update
• Documentation
• Other (describe):

Test plan

• Unit tests (task test)
• E2E tests (task test-e2e)
• Linting (task lint-fix)
• Manual testing (describe below)

Changes

File	Change

Does this introduce a user-facing change?

Implementation plan

Approved implementation plan

Special notes for reviewers

[Copilot]

Pull request overview

Adds vMCP config scaffolding support to the pkg/vmcp/cli package, enabling generation of a commented starter YAML config by discovering workloads in a ToolHive group and writing the result to a file or writer.

Changes:

• Introduce Init(ctx, InitConfig) to discover group workloads via an injected workloads.Discoverer and render a commented YAML starter config.
• Implement output routing to either an io.Writer (stdout-style) or a file written with 0o600 permissions.
• Add unit tests for writer/file output, empty groups, nil-backend skipping, discovery errors, YAML load+validate, file permissions, and input validation.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
pkg/vmcp/cli/init.go	Implements workload discovery, YAML template rendering, and output writing for thv vmcp init scaffolding.
pkg/vmcp/cli/init_test.go	Adds unit test coverage for init scaffolding behavior and output validity/permissions.

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[codecov]

Codecov Report

❌ Patch coverage is 70.83333% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.22%. Comparing base (5342824) to head (98a1b57).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/vmcp/cli/init.go	70.83%	12 Missing and 9 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4903      +/-   ##
==========================================
- Coverage   69.25%   69.22%   -0.04%     
==========================================
  Files         537      538       +1     
  Lines       55380    55452      +72     
==========================================
+ Hits        38354    38385      +31     
- Misses      14080    14117      +37     
- Partials     2946     2950       +4     

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

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[github-actions]

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[github-actions]

✅ PR size has been reduced below the XL threshold. The size review has been dismissed and this PR can now proceed with normal review. Thank you for splitting this up!

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

pkg/vmcp/cli/init.go:222

• When writing to an arbitrary io.Writer, Write is allowed to return a short write with a nil error. Currently the code ignores the returned byte count, so it could silently truncate output. Consider using io.Copy from a bytes.Reader (or explicitly checking n == len(content) and returning io.ErrShortWrite otherwise).

	return nil
}

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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