ci: restructure Go gate into separate jobs, add knip and svelte strict check

Go: go-build gates three parallel jobs (go-vet, golangci-lint, go-mod-tidy) which gate test+race.
Frontend: add knip (between deps and QC) and svelte-check --fail-on-warnings (after build).
QC now gates on build, knip, and svelte strict.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

.gitea/workflows/ci.yaml

@@ -17,8 +17,42 @@ env:
   POSTGRES_DB: mydb
 
 jobs:
-  vet:
+  go-build:
-    name: Go gate
+    name: Go build
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: sh
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.26"
+          cache: false
+
+      - name: Cache Go modules
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-${{ hashFiles('backend/go.sum') }}-build
+          restore-keys: |
+            ${{ runner.os }}-go-
+
+      - name: Fix node toolcache path for Post-step cleanup
+        run: |
+          mkdir -p /opt/hostedtoolcache/node/22.23.1/x64/bin
+          ln -sf /usr/local/bin/node /opt/hostedtoolcache/node/22.23.1/x64/bin/node
+
+      - name: Build
+        run: go build ./...
+        working-directory: backend
+
+  go-vet:
+    name: Go vet
+    needs: [go-build]
     runs-on: ubuntu-latest
     defaults:
       run:
@@ -46,10 +80,6 @@ jobs:
           mkdir -p /opt/hostedtoolcache/node/22.23.1/x64/bin
           ln -sf /usr/local/bin/node /opt/hostedtoolcache/node/22.23.1/x64/bin/node
 
-      - name: Build
-        run: go build ./...
-        working-directory: backend
-
       - name: Vet (dev tags)
         run: go vet -tags "test,dev" ./...
         working-directory: backend
@@ -58,12 +88,72 @@ jobs:
         run: go vet -tags "test,!dev" ./...
         working-directory: backend
 
+  go-lint:
+    name: golangci-lint
+    needs: [go-build]
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: sh
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.26"
+          cache: false
+
+      - name: Cache Go modules
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-${{ hashFiles('backend/go.sum') }}-lint
+          restore-keys: |
+            ${{ runner.os }}-go-
+
+      - name: Fix node toolcache path for Post-step cleanup
+        run: |
+          mkdir -p /opt/hostedtoolcache/node/22.23.1/x64/bin
+          ln -sf /usr/local/bin/node /opt/hostedtoolcache/node/22.23.1/x64/bin/node
+
       - name: golangci-lint
         run: |
           go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
           golangci-lint run ./...
         working-directory: backend
 
+  go-mod-tidy:
+    name: go mod tidy
+    needs: [go-build]
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: sh
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.26"
+          cache: false
+
+      - name: Cache Go modules
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/go/pkg/mod
+            ~/.cache/go-build
+          key: ${{ runner.os }}-go-${{ hashFiles('backend/go.sum') }}-tidy
+          restore-keys: |
+            ${{ runner.os }}-go-
+
+      - name: Fix node toolcache path for Post-step cleanup
+        run: |
+          mkdir -p /opt/hostedtoolcache/node/22.23.1/x64/bin
+          ln -sf /usr/local/bin/node /opt/hostedtoolcache/node/22.23.1/x64/bin/node
+
       - name: go mod tidy check
         run: |
           cp go.sum go.sum.bak
@@ -75,7 +165,7 @@ jobs:
 
   test:
     name: Tests (${{ matrix.label }})
-    needs: [vet, vulns]
+    needs: [go-vet, go-lint, go-mod-tidy, vulns]
     runs-on: ubuntu-latest
     defaults:
       run:
@@ -147,7 +237,7 @@ jobs:
 
   race:
     name: Race (${{ matrix.label }})
-    needs: [vet, vulns]
+    needs: [go-vet, go-lint, go-mod-tidy, vulns]
     runs-on: ubuntu-latest
     defaults:
       run:
@@ -340,6 +430,37 @@ jobs:
           console.log('All overrides appear necessary');
           "
 
+  knip:
+    name: Knip
+    needs: [frontend-deps]
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: sh
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Fix node toolcache path for Post-step cleanup
+        run: |
+          mkdir -p /opt/hostedtoolcache/node/22.23.1/x64/bin
+          ln -sf /usr/local/bin/node /opt/hostedtoolcache/node/22.23.1/x64/bin/node
+
+      - name: Restore npm dependencies
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.npm
+            frontend/node_modules
+          key: ${{ runner.os }}-npm-${{ hashFiles('frontend/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-npm-
+
+      - name: Install dependencies
+        run: cd frontend && npm ci
+
+      - name: Run knip
+        run: cd frontend && npx knip
+
   frontend-build:
     name: Frontend build
     runs-on: ubuntu-latest
@@ -370,9 +491,43 @@ jobs:
       - name: Build
         run: cd frontend && npm run build
 
+  frontend-svelte-strict:
+    name: Svelte strict check
+    needs: [frontend-build]
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: sh
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Fix node toolcache path for Post-step cleanup
+        run: |
+          mkdir -p /opt/hostedtoolcache/node/22.23.1/x64/bin
+          ln -sf /usr/local/bin/node /opt/hostedtoolcache/node/22.23.1/x64/bin/node
+
+      - name: Restore npm dependencies
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.npm
+            frontend/node_modules
+          key: ${{ runner.os }}-npm-${{ hashFiles('frontend/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-npm-
+
+      - name: Install dependencies
+        run: cd frontend && npm ci
+
+      - name: svelte-kit sync
+        run: cd frontend && npx svelte-kit sync
+
+      - name: svelte-check (fail on warnings)
+        run: cd frontend && npx svelte-check --tsconfig ./tsconfig.json --fail-on-warnings
+
   frontend-qc:
     name: Frontend QC (${{ matrix.task }})
-    needs: [frontend-deps, frontend-build]
+    needs: [frontend-build, knip, frontend-svelte-strict]
     runs-on: ubuntu-latest
     defaults:
       run: