feat(notes): add Obsidian livesync stack (CouchDB) + Caddy entry

stacks/notes/: new stack with CouchDB 3 for obsidian-livesync sync backend.
Vault data at /config/couchdb/data; CORS must be configured post-deploy
via Fauxton (/_utils). Claude integration via CouchDB REST API documented
in compose comments.

Caddyfile: obsidian.ginnoir.com → couchdb:5984 (public for mobile sync).

stacks/notes/docker-compose.yml

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+# notes stack — personal knowledge base / PKM backbone.
+#
+# CouchDB powers obsidian-livesync for real-time Obsidian vault sync
+# across all devices. Vault data lives at /config/couchdb/data on SSD.
+#
+# POST-DEPLOY (one-time setup):
+#   1. Open https://obsidian.ginnoir.com/_utils and sign in as admin.
+#   2. Settings → CORS → Enable CORS, add origins:
+#        app://obsidian.md
+#        capacitor://localhost
+#        http://localhost
+#   3. In Obsidian: install the "Self-hosted LiveSync" plugin,
+#      point it at https://obsidian.ginnoir.com with your creds.
+#   4. Let the setup wizard create the 'obsidian' database.
+#
+# Claude integration:
+#   The CouchDB REST API is the read/write surface for the vault.
+#   All notes are docs in the 'obsidian' database.
+#   GET https://obsidian.ginnoir.com/obsidian/_all_docs?include_docs=true
+#   returns all notes; each doc has a 'data' field with the markdown content.
+
+services:
+  couchdb:
+    container_name: couchdb
+    image: couchdb:3
+    restart: unless-stopped
+    networks: [notes, edge]
+    environment:
+      COUCHDB_USER: ${COUCHDB_USER}
+      COUCHDB_PASSWORD: ${COUCHDB_PASSWORD}
+    volumes:
+      - /config/couchdb/data:/opt/couchdb/data
+      - /config/couchdb/etc:/opt/couchdb/etc/local.d
+    ports:
+      - "5984:5984"
+
+networks:
+  notes:
+    name: notes
+    driver: bridge
+  edge:
+    name: edge
+    external: true

stacks/notes/stack.env

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+# notes stack secrets — CouchDB for Obsidian livesync
+
+# CouchDB admin credentials.
+# Used by: obsidian-livesync plugin, CouchDB Fauxton admin UI at /_utils.
+COUCHDB_USER=admin
+COUCHDB_PASSWORD=couchdb_obs_p4ss_7x9k