ci: GitHub Pages now serves a redirect to loto.miti99.com

Replace the full build+publish flow with a tiny inline shell step that
emits two static HTML pages (out/index.html and out/master/index.html).
Each one carries:

  <meta http-equiv="refresh" content="0; url=https://loto.miti99.com/">
  <script>location.replace("https://loto.miti99.com" + ...)</script>

The script preserves path / query / hash, so
  /loto/                  → loto.miti99.com/
  /loto/master            → loto.miti99.com/master
  /loto/?x=1              → loto.miti99.com/?x=1

Cloudflare Pages stays canonical; this change just stops GH Pages from
serving a stale duplicate of the app and points old links at the live
domain instead.

The build:gh npm script is kept as a manual escape hatch for the rare
case where someone wants to deploy a real GH Pages copy by hand.

web/.github/workflows/deploy-github-pages.yml

@@ -1,4 +1,4 @@
-name: Deploy to GitHub Pages
+name: Deploy redirect to GitHub Pages
 
 on:
   push:
@@ -19,16 +19,43 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
-        with:
-          node-version: 20
-          cache: npm
-      - run: npm ci
-      - run: npm run build:gh
+      - name: Generate redirect pages
+        run: |
+          set -euo pipefail
+          DEST="https://loto.miti99.com"
+          mkdir -p out/master
+          cat > out/index.html <<HTML
+          <!doctype html>
+          <html lang="vi">
+            <head>
+              <meta charset="utf-8">
+              <meta name="viewport" content="width=device-width, initial-scale=1">
+              <title>Lô tô — đã chuyển sang ${DEST}</title>
+              <link rel="canonical" href="${DEST}/">
+              <meta http-equiv="refresh" content="0; url=${DEST}/">
+              <meta name="robots" content="noindex">
+              <script>
+                (function () {
+                  var path = location.pathname.replace(/^\/loto/, "");
+                  location.replace("${DEST}" + path + location.search + location.hash);
+                })();
+              </script>
+              <style>
+                body { font-family: system-ui, sans-serif; padding: 3rem 1.5rem; text-align: center; color: #475569; }
+                a { color: #6366f1; }
+              </style>
+            </head>
+            <body>
+              <p>Trang đã chuyển sang <a href="${DEST}/">${DEST}</a></p>
+            </body>
+          </html>
+          HTML
+          # Mirror to /master so deep links also redirect cleanly
+          cp out/index.html out/master/index.html
       - uses: actions/configure-pages@v5
       - uses: actions/upload-pages-artifact@v3
         with:
-          path: build
+          path: out
 
   deploy:
     needs: build

web/docs/deployment-guide.md

@@ -32,26 +32,40 @@ pushes to `main` trigger automatic builds + deploys.
 
 No GitHub Actions involved; no repo secrets needed.
 
-## GitHub Pages (parallel auto-deploy)
+## GitHub Pages (redirect-only)
 
-`.github/workflows/deploy-github-pages.yml` runs on every push to `main`,
-builds with `npm run build:gh` (basePath `/loto`), and publishes `build/`
-as a Pages artifact.
+`.github/workflows/deploy-github-pages.yml` no longer builds the app.
+It generates two tiny HTML pages (`/loto/index.html` and
+`/loto/master/index.html`) that immediately redirect to the canonical
+URL on Cloudflare Pages.
 
-URL: `https://tiennm99.github.io/loto`.
+The redirect uses both `<meta http-equiv="refresh">` (no-JS fallback)
+and a tiny inline script that preserves path / query / hash:
 
-CF Pages and GH Pages run in parallel — different URLs, different
-artifacts, no conflict. Drop GH Pages by deleting the workflow file.
+```js
+location.replace("https://loto.miti99.com" + path + search + hash);
+```
 
-### Manual GH Pages Deploy
+So `tiennm99.github.io/loto/` → `loto.miti99.com/` and
+`tiennm99.github.io/loto/master` → `loto.miti99.com/master`.
 
-If you'd rather export by hand:
+The redirect runs on every push to `main`. If you want full GH Pages
+serving back (instead of the redirect), restore the prior version of
+`.github/workflows/deploy-github-pages.yml` from git history — it ran
+`npm run build:gh` and uploaded the `build/` artifact.
+
+### Manual GH Pages Build (still available)
+
+If you ever want to build a real GH Pages export by hand:
 
 ```bash
 npm run build:gh
-# upload build/ to the GH Pages target
+# upload build/ to the GH Pages target manually
 ```
 
+`build:gh` script kept as an escape hatch — not used by the automated
+redirect workflow.
+
 ## Development Environment
 
 ### Local Dev
@@ -155,11 +169,12 @@ Generates:
 
 ## CI/CD Pipeline
 
-Both providers auto-deploy on push to `main`:
-- **Cloudflare Pages** — wired via the CF dashboard, builds with `npm run build`,
-  publishes to `loto.miti99.com`.
-- **GitHub Pages** — wired via `.github/workflows/deploy-github-pages.yml`,
-  builds with `npm run build:gh`, publishes to `tiennm99.github.io/loto`.
+Two pipelines run on push to `main`:
+- **Cloudflare Pages** (canonical) — wired via the CF dashboard, builds with
+  `npm run build`, publishes to `loto.miti99.com`.
+- **GitHub Pages** (redirect-only) — wired via
+  `.github/workflows/deploy-github-pages.yml`, deploys static redirect HTML
+  that forwards `tiennm99.github.io/loto/*` to `loto.miti99.com/*`.
 
 ## Performance Checklist
 

web/docs/project-overview-pdr.md

@@ -31,7 +31,7 @@ State is entirely client-side. Each page/card instance uses a unique localStorag
 
 ## Deployment
 
-- **Production**: dual auto-deploy on push to `main` — Cloudflare Pages at `loto.miti99.com` (CF dashboard, root basePath) and GitHub Pages at `tiennm99.github.io/loto` (`.github/workflows/deploy-github-pages.yml`, `/loto` basePath via `npm run build:gh`).
+- **Production**: Cloudflare Pages at `loto.miti99.com` (canonical, CF dashboard, root basePath). GitHub Pages serves only a redirect to the canonical URL via `.github/workflows/deploy-github-pages.yml`.
 - **Development**: `npm run dev` (local), `npm run dev:codeserver` (code-server via proxy).
 - **Build**: `npm run build` generates static export to `build/` directory.