docs: expand configuration docs for admin and BadgerDB

Update README to explain startup config precedence (defaults/env/admin overrides),
document admin/bootstrap and feature toggles, and clarify storage locations under
WARPBOX_DATA_DIR including BadgerDB metadata. Also refresh project layout to
include new config and metastore packages.docs: expand configuration docs for admin and BadgerDB

Update README to explain startup config precedence (defaults/env/admin overrides),
document admin/bootstrap and feature toggles, and clarify storage locations under
WARPBOX_DATA_DIR including BadgerDB metadata. Also refresh project layout to
include new config and metastore packages.

docs/tech.md

@@ -86,13 +86,45 @@ Tuning is done with:
 
 ## Configuration
 
-Runtime configuration is intentionally small.
+Runtime configuration is centralized in `lib/config`. Startup applies built-in
+defaults, environment variables, then safe BadgerDB settings overrides.
 
-| Variable | Default | Purpose |
-| --- | ---: | --- |
-| `WARPBOX_BOX_POLL_INTERVAL_MS` | `5000` | Status polling interval used by box pages. |
-| `WARPBOX_THUMBNAIL_BATCH_SIZE` | `10` | Number of thumbnail jobs per worker pass. |
-| `WARPBOX_THUMBNAIL_INTERVAL_SECONDS` | `30` | Delay between thumbnail worker passes. |
+Storage paths are derived from `WARPBOX_DATA_DIR`:
+
+```text
+<WARPBOX_DATA_DIR>/uploads
+<WARPBOX_DATA_DIR>/db
+```
+
+The admin account is bootstrapped from `WARPBOX_ADMIN_PASSWORD` when no admin
+user exists. If the password is empty, admin login stays disabled unless an
+admin user already exists in BadgerDB.
+
+Primary environment variables:
+
+- `WARPBOX_DATA_DIR`
+- `WARPBOX_ADMIN_PASSWORD`
+- `WARPBOX_ADMIN_USERNAME`
+- `WARPBOX_ADMIN_EMAIL`
+- `WARPBOX_ADMIN_ENABLED`
+- `WARPBOX_ALLOW_ADMIN_SETTINGS_OVERRIDE`
+- `WARPBOX_ADMIN_COOKIE_SECURE`
+- `WARPBOX_GUEST_UPLOADS_ENABLED`
+- `WARPBOX_API_ENABLED`
+- `WARPBOX_ZIP_DOWNLOADS_ENABLED`
+- `WARPBOX_ONE_TIME_DOWNLOADS_ENABLED`
+- `WARPBOX_RENEW_ON_ACCESS_ENABLED`
+- `WARPBOX_RENEW_ON_DOWNLOAD_ENABLED`
+- `WARPBOX_DEFAULT_GUEST_EXPIRY_SECONDS`
+- `WARPBOX_MAX_GUEST_EXPIRY_SECONDS`
+- `WARPBOX_GLOBAL_MAX_FILE_SIZE_BYTES`
+- `WARPBOX_GLOBAL_MAX_BOX_SIZE_BYTES`
+- `WARPBOX_DEFAULT_USER_MAX_FILE_SIZE_BYTES`
+- `WARPBOX_DEFAULT_USER_MAX_BOX_SIZE_BYTES`
+- `WARPBOX_SESSION_TTL_SECONDS`
+- `WARPBOX_BOX_POLL_INTERVAL_MS`
+- `WARPBOX_THUMBNAIL_BATCH_SIZE`
+- `WARPBOX_THUMBNAIL_INTERVAL_SECONDS`
 
 The HTTP listen address is configured through the CLI flag:
 
@@ -106,10 +138,13 @@ go run ./cmd run --addr :8080
 cmd/main.go              CLI setup
 lib/server/server.go     Gin engine setup and worker startup
 lib/server/handlers.go   HTTP handlers
+lib/server/admin.go      Admin handlers
 lib/routing/routes.go    Route table
 lib/boxstore/store.go    Box manifests, uploads, downloads, retention
 lib/boxstore/thumbnails.go
                           Thumbnail scanning and generation
+lib/config/config.go     Typed config and settings definitions
+lib/metastore/           BadgerDB metadata store
 lib/models/models.go     Shared data structures
 ```