DOC-14109 worktree support

[osfameron]

This seems to work for me for simple cases now, but I feel like I'm missing:

• checking if current working tree is a linked worktree.
• the worktrees: true key

[Copilot]

Pull request overview

Updates the docs preview tooling to better identify the current repo (including in worktree-like setups) and to refactor the Antora extension hook that rewrites the playbook during preview builds.

Changes:

• Derive PREVIEW_REPO via GitHub CLI instead of inferring from the local toplevel directory name.
• Refactor lib/preview.js to use a named rebuildPlaybook handler and add local path mapping logic intended to support worktrees.
• Adjust the Antora --extension path to be explicitly relative (./lib/preview.js).

Reviewed changes

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

File	Description
scripts/preview	Switches repo-name detection to gh repo view and tweaks Antora extension path.
lib/preview.js	Refactors playbook rebuild hook and adds local URL/path mapping logic aimed at worktree support.

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[Copilot]

isMainGitDir only treats a repo as valid when .git is a directory. Linked worktrees typically have a .git file pointing at the shared gitdir, so this logic will fail to recognize the current worktree checkout and fall back to the remote URL (triggering an unnecessary clone and breaking the intended worktree support). Adjust the detection to treat a .git file as a valid worktree (or parse git rev-parse --git-dir / git worktree list --porcelain to locate the right working tree).

[osfameron]

the intention is that the readdir checks every file, and returns the first one that does have a main git dir.

[simon-dew]

I checked out this PR in my local docs-site repo and ran ./scripts/preview --init.
Unfortunately, in my worktree, preview still fails with this message:

~/GitHub/docs-devex/release/7.6 (DOC-12088-udf-guides ✗) preview
🐇 Hello! I'm the Docs Build Rabbit
version 1.1.1

HTTP 401: Bad credentials (https://api.github.com/graphql)
Try authenticating with:  gh auth login
   Let's build this preview!
PREVIEW_BRANCH=DOC-12088-udf-guides
PREVIEW_REPO=
PREVIEW_START_PATH=.
PREVIEW_OVERRIDE=antora-playbook.preview.local.yml
PREVIEW_CONFIG=DOC-12088-udf-guides
PREVIEW_COMPONENT=server

[14:00:01.593] FATAL (antora): Oh no!  source not found in playbook.
        You need to add to 'antora-playbook.preview.yml' something like:

        content:
          sources:
          # add in the appropriate place
          - url: https://github.com/couchbaselabs/docs-devex.git
            branches: DOC-12088-udf-guides
            
    Cause: Error
        at notfound (/Users/simondew/GitHub/docs-site/lib/preview.js:184:12)
        at GeneratorContext.rebuildPlaybook (/Users/simondew/GitHub/docs-site/lib/preview.js:44:15)
        at Object.onceWrapper (node:events:634:26)
        at GeneratorContext.notify (/Users/simondew/GitHub/docs-site/node_modules/@antora/site-generator/lib/generator-context.js:59:49)
        at generateSite (/Users/simondew/GitHub/docs-site/node_modules/@antora/site-generator/lib/generate-site.js:11:19)
        at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
        at async Command.parseAsync (/Users/simondew/GitHub/docs-site/node_modules/commander/lib/command.js:936:5)

[osfameron]

Has been tested by @harini16r who also uses Worktrees, and solves her specific issue.
As it doesn't seem to introduce any regressions from my (non-worktree) testing, I'll merge, and see if it throws up anything else.