chore: prune Stainless-era CI cruft and vestigial release-doctor (#1364)

The Stainless templates left behind a bunch of CI scaffolding that's
no longer doing anything in this repo:

ci.yml
- `on.push.branches` filter listed Stainless-internal codegen branches
  (`integrated/**`, `stl-preview-*`, `codegen/**`, `codegen/stl/**`)
  that never land here. Replaced with `branches: [main]` so push runs
  fire only on merge.
- `on.pull_request.branches-ignore` filtered the same Stainless
  preview branches. Dropped — same reasoning.
- Job-level `if:` guards (`github.event_name == 'push' ||
  github.event.pull_request.head.repo.fork` etc.) existed to
  deduplicate the duplicate runs you get when both push + pull_request
  fire for a same-repo PR. Under the new `on:` shape (push only on
  main, pull_request unfiltered) each commit triggers exactly one run,
  so the dedup is unnecessary.
- `runs-on` toggled to `depot-ubuntu-24.04` when running under
  `stainless-sdks/increase-typescript`. We never run there. Simplified
  to `ubuntu-latest`.
- `'codegen metadata'` head-commit guard skipped CI for Stainless's
  codegen housekeeping commits. We don't push those.
- The build job's OIDC token + `upload-artifact.sh` step pushed build
  tarballs to `pkg.stainless.com/s` for Stainless's preview UI. Dead
  endpoint for us. Dropped along with the `id-token: write`
  permission it required.

release-doctor.yml + bin/check-release-environment
- The script was a literal no-op (`errors=()` array, never populated,
  always prints "ready"). It exists in templates as a pre-flight
  check for repos with publish secrets (PYPI_TOKEN etc.); this repo
  uses OIDC trusted publishing on npm so there's no token to check.
- Even with checks populated, the only failure mode it catches that
  the publish workflow doesn't is "secret literally not set" — which
  recovers in 30s by setting the secret and re-running publish.
  Without branch-protection enforcement (which we don't have), it's
  a soft warning, not a gate. Drop it entirely.

Author: mattt

.github/workflows/ci.yml

@@ -1,25 +1,14 @@
 name: CI
 on:
   push:
-    branches:
-      - '**'
-      - '!integrated/**'
-      - '!stl-preview-head/**'
-      - '!stl-preview-base/**'
-      - '!generated'
-      - '!codegen/**'
-      - 'codegen/stl/**'
+    branches: [main]
   pull_request:
-    branches-ignore:
-      - 'stl-preview-head/**'
-      - 'stl-preview-base/**'
 
 jobs:
   lint:
     timeout-minutes: 10
     name: lint
-    runs-on: ${{ github.repository == 'stainless-sdks/increase-typescript' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
-    if: (github.event_name == 'push' || github.event.pull_request.head.repo.fork) && (github.event_name != 'push' || github.event.head_commit.message != 'codegen metadata')
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
@@ -37,11 +26,7 @@ jobs:
   build:
     timeout-minutes: 5
     name: build
-    runs-on: ${{ github.repository == 'stainless-sdks/increase-typescript' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
-    if: (github.event_name == 'push' || github.event.pull_request.head.repo.fork) && (github.event_name != 'push' || github.event.head_commit.message != 'codegen metadata')
-    permissions:
-      contents: read
-      id-token: write
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
@@ -56,29 +41,10 @@ jobs:
       - name: Check build
         run: ./scripts/build
 
-      - name: Get GitHub OIDC Token
-        if: |-
-          github.repository == 'stainless-sdks/increase-typescript' &&
-          !startsWith(github.ref, 'refs/heads/stl/')
-        id: github-oidc
-        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
-        with:
-          script: core.setOutput('github_token', await core.getIDToken());
-
-      - name: Upload tarball
-        if: |-
-          github.repository == 'stainless-sdks/increase-typescript' &&
-          !startsWith(github.ref, 'refs/heads/stl/')
-        env:
-          URL: https://pkg.stainless.com/s
-          AUTH: ${{ steps.github-oidc.outputs.github_token }}
-          SHA: ${{ github.sha }}
-        run: ./scripts/utils/upload-artifact.sh
   test:
     timeout-minutes: 10
     name: test
-    runs-on: ${{ github.repository == 'stainless-sdks/increase-typescript' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
-    if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2