add CSP-clean static build, hardened nginx config, and container image

.gitignore

@@ -1,3 +1,4 @@
 node_modules/
 *.log
 assets/work/
+dist/

Dockerfile

@@ -0,0 +1,22 @@
+# syntax=docker/dockerfile:1
+# Static teaching site: bash assembles dist/ from the split source, then a pinned
+# nginx-unprivileged serves it. No Node build — build.sh is plain bash + coreutils.
+
+# ---- build stage ----------------------------------------------------------
+# Reusing the digest the site image already pins: it's a bookworm-slim base that is
+# verified and cached in the zot pull-through mirror, so this layer costs nothing
+# extra. Only bash/sed/find/install are used here — node itself is incidental.
+FROM node:22-bookworm-slim@sha256:d9f850096136edbc402debdd8729579a288aac64574ada0ff4db26b6ae58b0b2 AS build
+WORKDIR /app
+COPY . .
+RUN bash build.sh
+
+# ---- runtime stage --------------------------------------------------------
+# Same vetted digest as the site. Renovate keeps it current.
+FROM ghcr.io/nginx/nginx-unprivileged:1.28.0-alpine@sha256:c97ff0bf7cbae369953c6da1232ec14ad9f971d66360c5698db0856a4cd657a0
+
+COPY nginx/default.conf /etc/nginx/conf.d/default.conf
+COPY nginx/security-headers.conf /etc/nginx/security-headers.conf
+COPY --from=build /app/dist /usr/share/nginx/html
+
+EXPOSE 8080

README.md

@@ -4,7 +4,8 @@ Interactive scroll-driven teardown of Kubernetes / OpenShift / Docker, in the es
 Bat-Computer visual world (void `#070b14`, cyan `#3fbaf5` → magenta `#e879f9`).
 
 - **v2** (tag `v2`) — CSS `preserve-3d` diagrams. Parked: eyeballed px positions, misaligned at some widths.
-- **v3** (in progress) — Nano Banana 2 exploded hero shots, hand-sliced into `clip-path` parts and
+- **v3** (in progress) — ships PUBLIC at **learn.bztmon.com**.
+- **v3 build** — Nano Banana 2 exploded hero shots, hand-sliced into `clip-path` parts and
   scrubbed collapsed → hero with GSAP. Spec: `homelab/specs/SPEC-exploded-cluster-v3.md`.
 
 ## Layout

build.sh

@@ -0,0 +1,70 @@
+#!/usr/bin/env bash
+# Assemble dist/ — the CSP-clean static build served at learn.bztmon.com.
+#
+# The artifact build inlines GSAP and the app JS because the artifact CSP blocks every
+# external request. nginx has no such constraint, so here they stay SEPARATE files:
+# `script-src 'self'` holds with no 'unsafe-inline' exception, and the two GSAP bundles
+# (116KB, unchanged between deploys) become independently cacheable.
+set -euo pipefail
+IFS=$'\n\t'
+
+trap 'printf "build failed at line %s\n" "$LINENO" >&2' ERR
+
+here="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+cd -- "$here"
+
+dist="$here/dist"
+src_markup="ec2-part1.html"
+src_app="ec2-part2.html"
+
+for f in "$src_markup" "$src_app" gsap.min.js st.min.js; do
+  [[ -f "$f" ]] || { printf 'missing source: %s\n' "$f" >&2; exit 1; }
+done
+
+rm -rf -- "$dist"
+mkdir -p -- "$dist"
+
+# --- app.js: strip the single <script> wrapper part2 carries -----------------
+# part2 is exactly one <script>…</script> block; served standalone it must be raw JS.
+sed -e '1{/^[[:space:]]*<script>[[:space:]]*$/d}' \
+    -e '${/^[[:space:]]*<\/script>[[:space:]]*$/d}' \
+    -- "$src_app" > "$dist/app.js"
+
+if grep -qiE '</?script' -- "$dist/app.js"; then
+  printf 'app.js still contains a script tag — the wrapper strip did not match\n' >&2
+  exit 1
+fi
+
+# --- index.html: markup + external script refs -------------------------------
+{
+  cat -- "$src_markup"
+  cat <<'HTML'
+
+<script src="/gsap.min.js"></script>
+<script src="/st.min.js"></script>
+<script src="/app.js"></script>
+</body>
+</html>
+HTML
+} > "$dist/index.html"
+
+# No inline JS may survive into the served HTML, or the CSP silently kills the page.
+# Every <script> opening tag must carry a src=. (grep -E has no lookahead — list the
+# tags, then assert none of them lacks src.)
+if grep -oiE '<script[^>]*>' -- "$dist/index.html" | grep -qivE 'src='; then
+  printf 'index.html contains an inline <script> — CSP script-src self would block it\n' >&2
+  exit 1
+fi
+
+install -m 0644 -- gsap.min.js st.min.js "$dist/"
+
+# --- scene assets ------------------------------------------------------------
+if [[ -d assets/dist ]]; then
+  mkdir -p -- "$dist/assets"
+  find assets/dist -type f -print0 | while IFS= read -r -d '' f; do
+    install -m 0644 -- "$f" "$dist/assets/$(basename -- "$f")"
+  done
+fi
+
+printf 'built %s\n' "$dist"
+find "$dist" -type f -printf '  %-22f %8s bytes\n' | sort

nginx/default.conf

@@ -0,0 +1,51 @@
+# nginx config for the static teaching site, baked into the image.
+# Base: nginxinc/nginx-unprivileged (uid 101, listens on 8080).
+# Read-only rootfs in k8s: /tmp and /var/cache/nginx are emptyDir mounts.
+
+server {
+    listen       8080;
+    server_name  _;
+    root         /usr/share/nginx/html;
+    index        index.html;
+
+    server_tokens off;
+
+    # Behind the Cloudflare Tunnel on :443 while nginx listens on :8080 — without these,
+    # nginx emits ABSOLUTE redirects to http://host:8080/... and breaks every link.
+    absolute_redirect off;
+    port_in_redirect off;
+
+    include /etc/nginx/security-headers.conf;
+
+    # ---- Caching -------------------------------------------------------------
+    # Scene images are content-hashed at build time → safe to cache hard.
+    location /assets/ {
+        include /etc/nginx/security-headers.conf;
+        expires 1y;
+        add_header Cache-Control "public, immutable" always;
+    }
+
+    # Scripts are NOT fingerprinted yet — revalidate so a deploy actually propagates.
+    location ~* \.js$ {
+        include /etc/nginx/security-headers.conf;
+        add_header Cache-Control "no-cache" always;
+    }
+
+    location ~* \.html$ {
+        include /etc/nginx/security-headers.conf;
+        add_header Cache-Control "no-cache" always;
+    }
+
+    # ---- Routing -------------------------------------------------------------
+    location / {
+        try_files $uri $uri/ $uri.html =404;
+    }
+
+    # ---- Compression ---------------------------------------------------------
+    # WebP/PNG are already compressed — gzipping them burns CPU for nothing.
+    gzip on;
+    gzip_comp_level 6;
+    gzip_min_length 1024;
+    gzip_types text/plain text/css application/javascript application/json image/svg+xml;
+    gzip_vary on;
+}

nginx/security-headers.conf

@@ -0,0 +1,19 @@
+# Shared security headers. `include`d in the server block AND in every location that
+# sets its own add_header — a location-level add_header REPLACES inherited headers
+# rather than merging them (the classic nginx footgun).
+#
+# HSTS is host-scoped: NO includeSubDomains / preload, because the *.bztmon.com
+# wildcard points elsewhere and forcing HTTPS estate-wide from here would be reckless.
+# HTTP->HTTPS upgrade is Cloudflare's job.
+add_header Strict-Transport-Security "max-age=31536000" always;
+
+# script-src 'self' with NO 'unsafe-inline'. build.sh externalises every script and
+# hard-fails if an inline <script> reaches dist/, so this holds without an exception.
+# style-src needs 'unsafe-inline': GSAP animates by writing inline style attributes.
+add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; font-src 'self'; connect-src 'self'; worker-src 'self'; manifest-src 'self'; object-src 'none'; base-uri 'self'; form-action 'self'; frame-ancestors 'none'; upgrade-insecure-requests" always;
+add_header X-Content-Type-Options "nosniff" always;
+add_header X-Frame-Options "DENY" always;
+add_header Referrer-Policy "strict-origin-when-cross-origin" always;
+add_header Permissions-Policy "camera=(), microphone=(), geolocation=(), payment=(), usb=(), interest-cohort=()" always;
+add_header Cross-Origin-Opener-Policy "same-origin" always;
+add_header Cross-Origin-Resource-Policy "same-origin" always;