Phase 2: Mode A static site — build, serve, search, stage panel

One Go binary serves a pre-rendered site. No Node, no bundler, no node_modules:
htmx and the SSE extension are vendored files, Markdown and code highlighting
run at build time (goldmark + chroma), and the server only writes files.

Implements docs/phase-2-static-site.md:

  2.1 service skeleton   cmd/build (content -> dist), cmd/server (dist -> HTTP),
                         env-configured, 127.0.0.1:8096, /healthz with separate
                         static / ai / search readiness, --health-check probe,
                         deploy/compose.yml + deploy/Dockerfile at 120m
  2.2 rendering          templ components (Layout, Nav, PillarCard, Stage,
                         EvidenceTable, CodeBlock, Timeline, Footer);
                         `make generate` is a build step and is byte-stable
  2.3 navigation         six-area rail, <details> disclosure under 900px,
                         breadcrumbs, aria-current, L1/L2/L3 with artefact pages
  2.4 stage panel        internal/stage owns the contract; RouteDriver (fragment
                         swap) and SSEDriver (event stream) differ only in the
                         Binding, never in layout. fragment ids live in the
                         contract so route files, links and streamed frames agree
  2.5 search             SQLite FTS5 over titles and body, rebuilt by the build;
                         one handler returns a page without HTMX, a fragment with
                         it. Visitors' FTS operators are never honoured
  2.6 quality floor      print stylesheet, JS-off navigation, focus states,
                         semantic landmarks, dark default; security headers

Definition of Done evidence (see issue AUD-142):
  A1  all pages 200 in a network namespace with no external route
  one binary serves the site; make dist writes 45 pages, 86 fragments, 40 docs
  templ generate is deterministic (md5 identical across runs)
  6 L1 + 6 L2 pages, artefact pages reachable in <= 3 clicks
  FTS5 returns sensible hits for zigbee / signage / routing (tested)
  Lighthouse 100 performance and 100 accessibility, mobile and desktop
  first byte well inside 100ms over loopback (test)
  panel renders from a route driver and re-points at the stream untouched
  print legible: /edge/ renders to a 3-page PDF with the print stylesheet

Also fixes found while finishing the build:
  - reject "." / ".." path segments before ServeMux redirects them into a file
    outside the asset directory (/static/../build.json now 404, was 307->200)
  - make test is the real gate: go test ./... plus the validator self-test

deploy/Dockerfile

@@ -0,0 +1,29 @@
+# Runtime image for the Mode A site (docs/phase-2-static-site.md §2.1).
+#
+# The image contains no toolchain: `make build dist` on the build host produces
+# bin/resume-server and dist/, and the image just carries them. That keeps the
+# runtime offline and small, and it means the deployed bytes are the bytes that
+# were built and tested, not a second compile.
+#
+# Build context is the repository root:
+#
+#	make build dist
+#	docker build -f deploy/Dockerfile -t ai-resume:local .
+#
+# Phase 3 (§3.1) owns the release directory, the compose invocation and the
+# rollback; this file only describes the process that runs.
+
+FROM gcr.io/distroless/static-debian12:nonroot
+
+COPY bin/resume-server /usr/bin/resume-server
+COPY dist/ /srv/site
+
+# 0.0.0.0 is inside the container's own network namespace only. The host
+# publishes the port on 127.0.0.1 (see deploy/compose.yml), which is what keeps
+# Caddy the only public listener.
+ENV RESUME_ADDR=0.0.0.0:8096 \
+    RESUME_DIST=/srv/site
+
+EXPOSE 8096
+USER nonroot:nonroot
+ENTRYPOINT ["/usr/bin/resume-server"]