Add Quartz service for serving Obsidian notes at /notes/

Replaces the custom Go/Vue notes system with Quartz v4, a polished
static site generator for Obsidian vaults. Mounts OBSIDIAN_DIR as the
Quartz content directory and serves it at /notes/ with hot-reload via
`npx quartz build --serve`.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

quartz/entrypoint.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+set -e
+
+envsubst '${DOMAIN}' \
+  < /quartz/quartz.config.ts.template \
+  > /quartz/quartz.config.ts
+
+exec npx quartz build --serve --port "${QUARTZ_PORT:-8080}"