feat: implement email validation, CI/CD pipeline, migration history, and web templates

Email validation:
- Replace @/. check with net/mail.ParseAddress on register
- Add size limit check (max 254 chars, RFC 5321)

CI/CD Pipeline:
- Add .gitea/workflows/ci.yml (lint → test → build → docker push)
- Registry: gitea.mrixs.me/Mrixs/MrixsCraft-server
- Push only on main branch

Database:
- Add migrations/002_migration_history.sql (tracking applied migrations)
- Add migrations/README.md (manual apply instructions)

Web Templates:
- Add base.html with Minecraft-themed layout (dark + green accent)
- Add index.html, login.html, register.html with POST forms
- Rewrite templates.go for data-driven rendering with pageData struct
- Fallback placeholder preserved when templates dir missing

.gitea/workflows/ci.yml

@@ -0,0 +1,90 @@
+name: CI
+
+on:
+  push:
+    branches: ["**"]
+  pull_request:
+    branches: ["main"]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.25"
+
+      - name: go vet
+        run: go vet ./...
+
+      - name: gofmt check
+        run: |
+          fmt=$(gofmt -l .)
+          if [ -n "$fmt" ]; then
+            echo "Files needing formatting:"
+            echo "$fmt"
+            exit 1
+          fi
+
+  test:
+    runs-on: ubuntu-latest
+    needs: lint
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.25"
+
+      - name: Run tests
+        run: go test ./... -v -race -cover
+
+  build:
+    runs-on: ubuntu-latest
+    needs: test
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.25"
+
+      - name: Build binary
+        run: go build -o mrixscraft-server ./cmd/server
+
+      - name: Upload artifact
+        if: github.ref == 'refs/heads/main'
+        uses: actions/upload-artifact@v4
+        with:
+          name: mrixscraft-server
+          path: mrixscraft-server
+
+  docker:
+    runs-on: ubuntu-latest
+    needs: build
+    if: github.ref == 'refs/heads/main'
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to Gitea Registry
+        uses: docker/login-action@v3
+        with:
+          registry: gitea.mrixs.me
+          username: ${{ secrets.GITEA_USERNAME }}
+          password: ${{ secrets.GITEA_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          push: true
+          tags: |
+            gitea.mrixs.me/Mrixs/MrixsCraft-server:latest
+            gitea.mrixs.me/Mrixs/MrixsCraft-server:${{ github.sha }}
+          cache-from: type=registry,ref=gitea.mrixs.me/Mrixs/MrixsCraft-server:latest
+          cache-to: type=inline