C0: fix Caddyfile try_html — handle_errors can't nest inside handle{}

The kind=static branch added in #342 put handle_errors inside the
@host handle{} block. handle_errors is a top-level site-block directive,
not an ordered HTTP handler, so Caddy refuses to load the config:

  parsing caddyfile tokens for 'handle': directive 'handle_errors'
  is not an ordered HTTP handler

This crash-loops the whole reverse proxy and takes down every
*.ops.eblu.me service. Tripped today during the live cv/docs cutover.

Fix: drop handle_errors and append /404.html as the final try_files
candidate. The 404 page is served with status 200 instead of 404, but
that's acceptable for a human-facing curated 404 — the page renders
correctly. Documented inline.

The running Caddy on indri already has the fixed config (deployed
manually during the cutover); this lands the fix in main so future
provision-indri --tags caddy runs don't re-break it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ansible/roles/caddy/templates/Caddyfile.j2

@@ -42,11 +42,11 @@
 		header @{{ service.name }}_dl{{ loop.index }} Content-Disposition `attachment; filename="{{ dl.filename }}"`
 {% endfor %}
 {% if service.try_html | default(false) %}
-		try_files {path} {path}/ {path}.html
+		# Quartz clean URLs: path → path/ → path.html → /404.html (200).
-		handle_errors 404 {
+		# Caddy's handle_errors is a top-level directive and can't live in
-			rewrite * /404.html
+		# this nested handle, so the 404 page rides as the final try_files
-			file_server
+		# candidate (served with 200 — acceptable for a human-facing 404).
-		}
+		try_files {path} {path}/ {path}.html /404.html
 {% endif %}
 		file_server
 {% else %}