fix: bind mounts from DOCKER_PATH + real storage reads from disk

docker-compose.yml:
- Switch from named volumes back to bind mounts driven by DOCKER_PATH in .env
- DOCKER_PATH/config → /config, DOCKER_PATH/data → /data
- Works with both Windows paths (C:\...) and Linux paths (/opt/...)

server.go:
- Wire in storage.Store so documents query reads real .adoc files from disk
- handleDocuments: calls store.List("") and store.Read(slug) for actual content
- extractTitle: parses first "= Title" line from AsciiDoc, falls back to slug
- handleSetup: also initialises store after writing config so docs appear immediately
- Single document query (document(slug:...)) reads and returns full content

.env.example:
- Clarify DOCKER_PATH usage with Windows and Linux examples
- Show resulting directory layout on host

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

.env.example

@@ -16,21 +16,27 @@ REGISTRY=192.168.0.19:5000
 IMAGE_TAG=latest
 
 
-# ── Host paths ─────────────────────────────────────────────────────────────────
-# Base directory — all data lives under this path.
-# Adjust to wherever you want to store Archivum data on the host.
-ARCHIVUM_BASE=/opt/archivum
-
-# Configuration directory (config.json, settings.json).
-# The Setup Wizard will create config.json here on first access.
-ARCHIVUM_CONFIG=/opt/archivum/config
-
-# AsciiDoc wiki files + git repository root.
-ARCHIVUM_WIKI=/opt/archivum/wiki
-
-# SQLite database directory.
-# The database file will be created as archivum.db inside this directory.
-ARCHIVUM_DB=/opt/archivum/db
+# ── Host paths (docker-compose.yml) ───────────────────────────────────────────
+# DOCKER_PATH is the base directory on the HOST where data is stored.
+# docker-compose.yml maps:
+#   DOCKER_PATH/config  →  /config  (config.json written here by Setup Wizard)
+#   DOCKER_PATH/data    →  /data    (wiki files in data/wiki, db in data/db)
+#
+# Windows example (Docker Desktop):
+#   DOCKER_PATH=C:\Repo\AW\Archivum\docker
+#
+# Linux / WSL example:
+#   DOCKER_PATH=/opt/archivum
+#
+# The directory structure on the host will be:
+#   DOCKER_PATH/
+#   ├── config/
+#   │   └── config.json      ← written by Setup Wizard
+#   └── data/
+#       ├── wiki/            ← put your .adoc files here
+#       └── db/
+#           └── archivum.db  ← auto-created
+DOCKER_PATH=C:\Repo\AW\Archivum\docker
 
 
 # ── Network ────────────────────────────────────────────────────────────────────