feat(skill): offer Action or GitHub App mode, and check the permission first

[akf66]

The App exists at github.com/apps/orcacode-review, but the skill only knew about the Action. Now it asks which, and routes.

The ordering is the point

It probes what the user can actually do before offering the choice:

gh api /repos/<o>/<n> --jq .permissions.admin
gh api /orgs/<o>/memberships/<user> --jq .role

Installing a GitHub App is a permission grant — GitHub requires a human to approve it on an authorization page, and there is no REST endpoint that does it on someone's behalf. Deliberate, not a gap.

So offering App mode to a plain org member walks them to a page that stops them. Verified against this repo:

{"admin": false, "owner": "Continuum-AI-Corp", "ownerType": "Organization"}
role: member

The account we've been running all day could not complete App mode. The skill now says that up front instead of finding out three steps in.

App mode hands over a link

https://github.com/apps/orcacode-review/installations/new

It prints the URL and only optionally opens it. A tool that silently calls open in an SSH session, a container, or CI leaves the user waiting on a browser that never appears.

It also says to pick this repository rather than "all repositories" — a much larger grant, and on a paid plan a much larger bill.

Verification is honest about its limits

Route	Why not
GET /repos/{o}/{r}/installation	Needs the App's own JWT. No user token can produce one — confirmed, 401.
GET /orgs/{o}/installations	Needs admin:org. Not worth asking for write-level org scope to read one flag.

Fallback: open a PR and look for the bot review — the thing the user actually cares about.

The failure mode this choice creates

Both installed → two reviews per PR, double spend. Documented in the skill and in troubleshooting.md, with the note that removing the Action is the reversible half — revoking an App installation is a permission change only an admin can make.

Also

Renames Action step 5 from "Enable the app". It means the OrcaRouter console, which now reads as the GitHub App and would send people to the wrong place.

Tests

Four new, pinning what would rot quietly: both modes present and linked, the permission warning ordered before the routing line, no claim the install is automatable, the print-don't-just-open rule, and the conflict documented in both files.

393 passing on top of #28. 1.3.0 — merging publishes it.