Add Dockerfile for self-hosted deployment, bump build.sh to Zola 0.23.1

Adds a multi-stage Dockerfile (Node for llms.txt generation, the
official Zola image to build, static-web-server to serve) for
deploying via Dokploy/Docker instead of Cloudflare Pages. This is an
additional path, not a replacement - wrangler.toml and the Cloudflare
build.sh remain in place as an option.

Also bumps build.sh's pinned ZOLA_VERSION from 0.22.1 to 0.23.1: the
prior commit migrated every template to Tera v2 syntax (components,
spread operator, native slicing), which 0.22.1 can't parse - confirmed
by a live Cloudflare build failure on this branch. Keeping build.sh
and the Dockerfile on the same Zola version avoids maintaining two
template dialects across the two deploy paths.

Verified: `docker build` succeeds, the container serves the homepage,
a post, the youtube embed, and a proper 404; `build.sh` also runs
clean standalone (simulating the Cloudflare build) and produces a
fully populated public/.

Dockerfile

@@ -0,0 +1,21 @@
+# Multi-stage build: generate llms.txt with Node, build the site with Zola,
+# then serve the static output with static-web-server.
+#
+# This is the Dokploy/self-hosted deployment path. It's independent of the
+# Cloudflare Pages path (`npm run deploy` / wrangler.toml) - that stays in
+# place as an option, this doesn't replace it.
+
+FROM node:22-slim AS llms
+WORKDIR /project
+COPY . .
+RUN node scripts/generate-llms.mjs
+
+FROM ghcr.io/getzola/zola:v0.23.1 AS zola
+WORKDIR /project
+COPY . .
+COPY --from=llms /project/static/llms.txt static/llms.txt
+RUN ["/zola", "build"]
+
+FROM ghcr.io/static-web-server/static-web-server:2
+COPY --from=zola /project/public /public
+EXPOSE 80