restructure: move web app into sources/

All served files (index.html, core/, pages/, components/, vendor/,
config.json, icons.json, favicon.svg) are now under sources/.
build.sh and components.yml stay at the repo root.
build.sh updated: WEB_DIR → sources/, MANIFEST stays at SCRIPT_DIR.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>

sources/config.json

@@ -0,0 +1,5 @@
+{
+  "netbox_url": "http://netbox.local",
+  "netbox_token": "your-token-here",
+  "agent_url": "http://127.0.0.1:8080"
+}