Run the same checks on Linux that the Windows scripts run

The product could only reach a GPU through one hard-coded route: `wsl.exe -d
Ubuntu`, a device named "RTX 4090", and launch scripts that existed only as
PowerShell. On this machine `WSL_DISTRO_NAME` is already set, so the local
shell is Linux and the wsl.exe hop was unnecessary; on any other Linux host
it is impossible. Every SGLang, vLLM and KTransformers profile was reported
"missing" here even with a working 4090.

profiles.py now asks the host what it is instead of assuming: `uses_wsl()`
is false inside WSL and only true when wsl.exe is actually on PATH,
`host_shell()` runs `bash -lc` directly or through `wsl.exe -d
settings.wsl_distro`, `gpu_available()` replaced `wsl_gpu_available()`, and
`launch_script()` picks the .sh twin on a Linux host and the .ps1 on a
Windows one. The schema field `wsl_gpu` became `gpu_available` because the
old name lied on Linux.

Training no longer fails on a card name. `cuda_bf16_training()` gates on
cuda_available plus bf16_supported, which the training environment already
records, so an RTX 5090 or a 4080 passes and a non-BF16 4090 still fails.

Fourteen .sh twins cover the six launch profiles plus install, verify,
serve, download and finetune; the six WSL-hopping .ps1 files read
ELY_EYE_WSL_DISTRO instead of Ubuntu. PowerShell parsing is not verified
here because no pwsh exists on this host.

ci.yml runs pytest, ruff, go build/vet/test/gofmt, the Vite build and a
docker build-plus-curl on every push. To make that lint gate mean anything,
the 17 pre-existing ruff findings across backend/src are cleared: 14
mechanical fixes plus three probe handlers that now name the failure
families they absorb (OSError, SubprocessError, ValueError) instead of
catching Exception.

Verification: pytest 239 passed; ruff check backend/src bench clean (17 at
HEAD); mypy on the 12 touched files 14 errors, identical at HEAD; pyright on
the same files 8 errors, identical at HEAD; bash -n clean on all 15 .sh.

.github/workflows/ci.yml

@@ -0,0 +1,67 @@
+name: ci
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  backend:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+          cache: pip
+      - run: pip install -e ./backend
+      - run: python -m pytest -q
+      - run: pip install ruff==0.16.10 && ruff check backend/src bench
+
+  mcp:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "1.25"
+          cache-dependency-path: ely-eye-mcp/go.sum
+      - name: Build, vet and test
+        working-directory: ely-eye-mcp
+        run: go build ./... && go vet ./... && go test ./...
+      - name: gofmt is clean
+        working-directory: ely-eye-mcp
+        run: test -z "$(gofmt -l .)"
+
+  interface:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+          cache: npm
+          cache-dependency-path: frontend/package-lock.json
+      - run: npm ci && npm run build
+        working-directory: frontend
+
+  image:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build the image from a clean clone
+        run: docker build -t ely-eye:ci .
+      - name: The container answers on both faces
+        run: |
+          docker run -d --name elyeye -p 8765:8765 ely-eye:ci
+          url=http://127.0.0.1:8765/api/status
+          for attempt in $(seq 1 30); do
+            curl -fsS "$url" -o /tmp/status.json && break
+            sleep 2
+          done
+          cat /tmp/status.json
+          curl -fsS http://127.0.0.1:8765/ | grep -q '<div id="root">'
+          docker logs elyeye