feat: Extension gallery infrastructure + V2 schema

[Niels Laute (niels9001)]

Summary

Sets up the complete extension gallery infrastructure for Command Palette, including:

Gallery Infrastructure

• extensions/ folder convention — each extension lives in its own subfolder with extension.json + icon
• JSON Schema (.github/schemas/extension.schema.json) — validates extension submissions
• Validation script (.github/scripts/validate.py) — PR-time checks (schema, icon, duplicates, naming)
• Generation script (.github/scripts/generate.py) — aggregates all extensions into root extensions.json
• CI workflows — PR validation + auto-regeneration on merge to main

V2 Extension Schema

• title (display name), author (object: name + url), installSources (array supporting multiple sources)
• Install source types: winget (id), msstore (id), url (uri)
• Simple slug IDs (e.g., media-controls)
• Optional category and tags fields

Documentation

• docs/CONTRIBUTING.md — step-by-step submission guide for 3P developers
• PR template with submission checklist
• Updated README with gallery overview and JSON endpoint

Sample Extension

• extensions/sample-extension/ — reference implementation for contributors

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[Copilot]

Pull request overview

Sets up a GitHub-hosted “extension gallery” pipeline for Command Palette by standardizing the on-repo extension submission format (V2 schema) and adding CI automation to validate submissions and generate a single aggregated extensions.json endpoint.

Changes:

• Introduces a V2 extension.json schema (author object + multiple install sources) and updates docs/templates accordingly.
• Adds PR-time validation and main-branch gallery generation workflows backed by Python scripts under .github/scripts/.
• Replaces the previous sample extension folder/metadata with a new extensions/sample-extension/ example and updates the generated extensions.json.

Reviewed changes

Copilot reviewed 11 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
extensions/sample-extension/icon.png	Adds an icon asset for the sample extension.
extensions/sample-extension/extension.json	Adds a V2-format sample extension submission.
extensions/microsoft.sample-extension/extension.json	Removes legacy V1 sample metadata.
extensions.json	Updates generated gallery output to V2 fields and new schema location.
docs/CONTRIBUTING.md	Updates contributor instructions to new folder/id conventions and V2 schema fields.
README.md	Updates repo structure + endpoint documentation to extensions.json at repo root.
.github/workflows/validate-pr.yml	Runs validator against changed extensions/** files in PRs using new script paths.
.github/workflows/generate-gallery.yml	Regenerates and commits extensions.json on merges to main.
.github/scripts/validate.py	Updates validator for new repo layout and V2 id rules.
.github/scripts/requirements.txt	Adds Python dependency pinning for validation/generation scripts.
.github/scripts/generate.py	Updates generator to output root extensions.json and new schema URL path.
.github/schemas/extension.schema.json	Defines the V2 extension submission JSON Schema.
.github/PULL_REQUEST_TEMPLATE.md	Updates submission checklist for new naming and install source types.

Comments suppressed due to low confidence (4)

.github/scripts/validate.py:28

• The script’s ImportError guidance still references pip install -r scripts/requirements.txt, but dependencies are now in .github/scripts/requirements.txt. Update that message so local runs point at the correct requirements file.
  extensions.json:2
• The gallery $schema URL points at .github/schemas/gallery.schema.json, but that file does not exist in the repository. Either add the gallery schema at that path (and ensure it’s published on main), or remove/update the $schema reference so it doesn’t 404.
  .github/scripts/generate.py:25
• GALLERY_SCHEMA_URL is set to ${BASE_RAW_URL}/.github/schemas/gallery.schema.json, but there is no gallery.schema.json under .github/schemas/ in this repo. This makes the $schema value in the generated extensions.json point to a non-existent URL; add the missing schema or adjust the URL/value accordingly.
  .github/scripts/validate.py:16
• The usage examples still reference python scripts/validate.py ..., but the script now lives under .github/scripts/validate.py. Update the remaining usage lines so they match the new path to avoid confusing local runs and copy/paste instructions.

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[Mike Griese (zadjii-msft)]

can an extension have multiple install sources? like, from the store INCLUSIVE_OR from winget?

[Niels Laute (niels9001)]

I was thinking we could let the user choose.. but maybe it's overkill? thoughts?