chore: add a verified Bun devcontainer

[Aymericr]

Ports the contributor work from #273 onto current main while preserving the original commit authorship.

What changed

• add a Bun 1.3 devcontainer with Git and GitHub CLI features
• pin resolved feature versions in the generated devcontainer lockfile
• install with the frozen workspace lockfile
• forward the editor port, 3002
• correct stale 3000 references in contributor and setup docs

Verification

• bun check
• bunx @devcontainers/cli up --workspace-folder .
• frozen bun install completed inside the new container
• bun dev reached the editor and IFC converter Ready states inside the container
• bun --filter editor dev reached Ready on 3002
• curl from inside the container returned HTTP 200 from http://127.0.0.1:3002 and loaded the built-in node registry

The disposable verification container was removed after the check.

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Note

Low Risk
Devcontainer and documentation-only changes; no runtime application or security logic is modified.

Overview
Adds a Pascal Editor dev container on oven/bun:1.3.0 with Git and GitHub CLI features, bun install --frozen-lockfile on create, and port 3002 forwarded for the editor.

Introduces devcontainer-lock.json to pin resolved versions for those container features.

Updates contributor/setup READMEs so local dev URLs and the documented default PORT use 3002 instead of 3000 (no application code changes in this diff).

^{Reviewed by Cursor Bugbot for commit 5024c50. Bugbot is set up for automated code reviews on this repo. Configure here.}