feat: ease scaffolding inputs with hub configuration

[gblanc-1a]

Description

Add a scaffoldDefaults section to hub configuration that pre-fills or skips scaffolding prompts, reducing repetitive input for users whose hub already defines organization-level values (org name, contacts, runner label, etc.).

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📝 Documentation update
• ♻️ Code refactoring (no functional changes)
• ⚡ Performance improvement
• 🧪 Test coverage improvement
• 🔧 Configuration/build changes

Related Issues

Closes #138

Changes Made

• Hub schema (schemas/hub-config.schema.json): Added scaffoldDefaults object with optional fields: githubOrg, githubRunner, organizationName, internalContact, legalContact, organizationPolicyLink. Strict additionalProperties: false to prevent unknown fields.
• TypeScript types (src/types/hub.ts): Added ScaffoldDefaults interface and wired it into HubConfig.
• ScaffoldCommand (src/commands/ScaffoldCommand.ts): runWithUI() now accepts an optional HubManager, loads scaffoldDefaults from the active hub, and passes them through to promptForProjectDetails, promptForOrganizationDetails, and promptForGitHubRunner. Org-level fields are skipped when hub defaults are present; githubOrg and githubRunner are pre-filled but still editable.
• Extension entry point (src/extension.ts): Passes this.hubManager to ScaffoldCommand.runWithUI().
• Scaffold utilities (src/utils/scaffoldUtils.ts): New helper resolveRunnerPattern() replaces {githubOrg} placeholders in runner strings; getGitHubUserIdentity() reads the GitHub session to pre-fill the author field.
• Documentation (docs/reference/hub-schema.md): Documented scaffoldDefaults object, runner pattern syntax, and prompt behavior table (skipped vs. pre-filled vs. always asked).
• Tests: Added test/unit/hubSchemaScaffoldDefaults.test.ts (schema validation for scaffoldDefaults) and test/utils/scaffoldUtils.test.ts (resolveRunnerPattern and getGitHubUserIdentity unit tests).

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing completed
• All existing tests pass

Manual Testing Steps

1. Configure a hub with scaffoldDefaults containing all six fields and scaffold a new GitHub project — verify org-level prompts are skipped and githubOrg/githubRunner are pre-filled
2. Configure a hub with only githubOrg set — verify other org fields are still prompted
3. Scaffold without any active hub — verify behavior is unchanged (all prompts shown)
4. Add an unknown property to scaffoldDefaults in a hub config — verify schema validation rejects it

Tested On

• macOS

• Windows

• Linux

• VS Code Stable

• VS Code Insiders

Screenshots

N/A — UX changes are in VS Code input boxes (pre-filled values / skipped prompts)

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published

Documentation

• README.md updated
• JSDoc comments added/updated
• No documentation changes needed

Additional Notes

The feature is fully backward-compatible: hubs without scaffoldDefaults behave exactly as before. The {githubOrg} placeholder in githubRunner is the only supported pattern — no general templating engine is introduced.

Reviewer Guidelines

Please pay special attention to:

• The skip logic in promptForOrganizationDetails — it short-circuits when any of the four org fields are present in hub defaults; verify this is the intended granularity vs. requiring all four
• The resolveRunnerPattern only supports {githubOrg} — confirm no other placeholders are needed
• Thread safety of getGitHubUserIdentity() — it uses createIfNone: false so it never triggers a sign-in prompt

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache License 2.0.