chore(release): goreleaser + CI workflows + v2 demo GIFs

Release infrastructure:
- .goreleaser.yml: builds 5-platform binaries (darwin/linux/windows
  x amd64/arm64), SHA-256 checksums, pre-release detection for -rc tags
- .github/workflows/release.yml: runs on any 'v*' tag — test -> build
  -> publish via goreleaser-action
- .github/workflows/ci.yml: test + vet + race detector on every push
  to main / v2-* and every PR
- .gitignore: extended to cover scan artifacts (gods-eye-*.json,
  report-*.json, *.stderr), YAML configs (god-eye.yaml, .god-eye.yaml),
  IDE state (.idea, .vscode, .cursor), Claude Code working notes
  (CLAUDE.md, .claude/), and the /god-eye build artifact

Demo GIFs recorded live against scanme.nmap.org (Nmap's authorized
test host):
- assets/wizard-demo.gif (272 KB): interactive setup walkthrough
- assets/live-scan.gif (37 KB): colorized event stream
- assets/ai-verbose.gif (122 KB): full AI cascade + end-of-scan brief

Legacy v0.1 assets removed:
- assets/demo.gif
- assets/demo-ai.gif

.github/workflows/ci.yml

@@ -0,0 +1,50 @@
+# Continuous integration — runs on every push to main and every PR.
+# Catches regressions early so the Release workflow on tag push doesn't
+# surprise us with a red test run when we least want it.
+
+name: CI
+
+on:
+  push:
+    branches: [ main, 'v2-*' ]
+  pull_request:
+    branches: [ main ]
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: Test & vet
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go-version: [ '1.21' ]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Go ${{ matrix.go-version }}
+        uses: actions/setup-go@v5
+        with:
+          go-version: ${{ matrix.go-version }}
+
+      - name: Cache Go modules
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cache/go-build
+            ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ matrix.go-version }}-${{ hashFiles('**/go.sum') }}
+
+      - name: Verify modules
+        run: go mod verify
+
+      - name: Build
+        run: go build ./...
+
+      - name: Vet
+        run: go vet ./...
+
+      - name: Test (race detector)
+        run: go test ./... -race -timeout 180s