Migrate theme from git submodule to Hugo Module (v0.2.2) (#25)

* Migrate theme from git submodule to Hugo Module (v0.2.2)

Drops themes/pager submodule in favor of a Hugo Module import pinned
in go.mod and vendored under _vendor/. Vendoring keeps CI and
Cloudflare Pages free of a Go toolchain requirement (only the
maintainer running `hugo mod get` / `hugo mod vendor` needs Go).

Theme bump v0.2.0 -> v0.2.2 covers the cosmetic cleanup from 0.2.1
(rounded-corners fix, stale Cascadia references, doc honesty) and
the self-hosted JS lint from 0.2.2. Because the theme now owns its
own ESLint + tsc --checkJs, the blog drops its mirror tooling:

- eslint.config.mjs, package.json (+ lock), and node_modules.
- `js-lint` / `js-typecheck` pre-commit hooks.
- `lint` CI job in perf.yml (budget + lighthouse remain).
- Required-status-checks on main updated to {budget, lighthouse}.

Docs also trimmed: PERFORMANCE.md stops documenting theme internals
(SCSS pipeline paths, the min-content gotcha story, font-family
declarations) and delegates implementation to the theme. The
blog-level rules - 14 KB single flight, zero JS, system fonts,
Lighthouse 100 - stay. README swaps the submodule instructions for
the Hugo Module bump flow.

* chore: drop stale tests/visual/ large-file exclude

The `exclude: ^tests/visual/.*-snapshots/.*\.png$` pattern targeted
Playwright visual-regression snapshots in a tests/ tree that was
retired in the v0.2.0 release. The 200 KB large-file guard has had
no paths to skip since; the line is dead weight.

---------

Co-authored-by: Przemysław Szypowicz <2733699+pszypowicz@users.noreply.github.com>

Author: pszypowicz

.github/workflows/perf.yml

@@ -21,7 +21,6 @@ jobs:
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd  # v5.0.1
         with:
-          submodules: recursive
           fetch-depth: 1
       - name: Install Hugo extended
         run: |
@@ -40,33 +39,12 @@ jobs:
       - name: Single-flight bench
         run: scripts/bench.sh
 
-  lint:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd  # v5.0.1
-        with:
-          submodules: recursive
-          fetch-depth: 1
-      - uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444  # v5.0.0
-        with:
-          node-version: '22'
-          cache: npm
-      - name: Install npm devDependencies
-        # --ignore-scripts blocks postinstall hooks so a malicious
-        # package-lock.json change cannot execute code during install.
-        run: npm ci --include=dev --ignore-scripts
-      - name: ESLint
-        run: npm run lint
-      - name: TypeScript check
-        run: npm run typecheck
-
   lighthouse:
     runs-on: ubuntu-latest
     needs: budget
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd  # v5.0.1
         with:
-          submodules: recursive
           fetch-depth: 1
       - name: Install Hugo extended
         run: |

.gitmodules

@@ -18,7 +18,6 @@ repos:
       - id: check-merge-conflict
       - id: check-added-large-files
         args: ["--maxkb=200"]
-        exclude: ^tests/visual/.*-snapshots/.*\.png$
       - id: mixed-line-ending
         args: ["--fix=lf"]
 
@@ -36,22 +35,8 @@ repos:
         language: system
         pass_filenames: false
         always_run: false
-        files: ^(content/|static/|themes/|config/|hugo\.toml)
+        files: ^(content/|static/|_vendor/|config/|hugo\.toml)
         description: >
           Build the site and enforce the byte / single-packet / zero-JS
           budgets defined in docs/PERFORMANCE.md. Only fires when site
           sources change.
-
-      - id: js-lint
-        name: ESLint (themes/pager/assets/js)
-        entry: npm run --silent lint
-        language: system
-        pass_filenames: false
-        files: ^(themes/pager/assets/js/|eslint\.config\.mjs$)
-
-      - id: js-typecheck
-        name: tsc --checkJs (themes/pager/assets/js)
-        entry: npm run --silent typecheck
-        language: system
-        pass_filenames: false
-        files: ^(themes/pager/assets/js/|themes/pager/jsconfig\.json$)

.pre-commit-config.yaml

@@ -33,8 +33,8 @@ scripts/http-verify.sh  # post-deploy: TLS 1.3, HTTP/3, Brotli, cache headers
 ## Layout
 
 - `content/` - posts and pages
-- `config/_default/` - Hugo config split by concern (hugo, params, menu, markup, languages)
-- `themes/pager/` - theme submodule
+- `config/_default/` - Hugo config split by concern (hugo, params, menu, markup, module, languages)
+- `_vendor/` - Hugo Modules vendored tree (theme lives here; pinned in `go.mod`)
 - `scripts/` - budget and perf verification
 - `docs/` - public performance charter
 
@@ -44,14 +44,14 @@ scripts/http-verify.sh  # post-deploy: TLS 1.3, HTTP/3, Brotli, cache headers
 
 ```sh
 git checkout -b <topic>             # branch off main
-# edit, commit (pre-commit runs budget / lint / typecheck on staged files)
+# edit, commit (pre-commit runs the perf budget on staged files)
 git push -u origin <topic>
 gh pr create --fill                 # opens PR against main
 ```
 
 Opening the PR triggers:
 
-- **GitHub Actions** (`.github/workflows/perf.yml`) - runs `budget`, `lint`, `lighthouse` jobs. Required to pass before merge.
+- **GitHub Actions** (`.github/workflows/perf.yml`) - runs `budget` and `lighthouse` jobs. Required to pass before merge.
 - **Cloudflare Pages preview** - auto-deploys the branch to `https://<branch>.blog-szypowicz.pages.dev/`. Open it on the iPad / desktop to visually verify.
 
 Once green:
@@ -62,7 +62,13 @@ gh pr merge --squash --delete-branch
 
 Production (`main` on Cloudflare Pages) rebuilds automatically from the merged commit.
 
-Theme changes (`themes/pager/`) follow the same pattern in the [`hugo-theme-pager`](https://github.com/pszypowicz/hugo-theme-pager) repo; merge theme PRs first, then bump the submodule pointer here via a blog PR.
+Theme changes happen in the [`hugo-theme-pager`](https://github.com/pszypowicz/hugo-theme-pager) repo. After a theme release, bump the pin here via:
+
+```sh
+hugo mod get github.com/pszypowicz/hugo-theme-pager@vX.Y.Z
+hugo mod vendor
+# commit go.mod, go.sum, and _vendor/ in a blog PR
+```
 
 ## License