Lock the site down to authenticated users only

All the ledger data is confidential (real client names, amounts,
associate balances) -- revoke 'access content' from the anonymous
role so nodes, taxonomy terms, and JSON:API all deny anonymous reads
(verified: JSON:API returns an empty data[] + "omitted" notice instead
of the records, /lignes and /dashboard 403).

Set the site's 403 page to /user/login: anonymous visitors hitting "/"
(the front page is /lignes) land on the login form instead of an
access-denied page; authenticated users still land on /lignes as
before since they still hold 'access content' via the authenticated
role.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

config/sync/system.site.yml

@@ -6,7 +6,7 @@ name: 'Figures Libres - Compta'
 mail: admin@example.com
 slogan: ''
 page:
-  403: ''
+  403: /user/login
   404: ''
   front: /lignes
 admin_compact_mode: false

config/sync/user.role.anonymous.yml

@@ -6,7 +6,6 @@ dependencies:
     - filter.format.restricted_html
   module:
     - filter
-    - system
 _core:
   default_config_hash: Tus1ZTNXKIOnrennR1hnTbc7wUPBXHTUm5UdCpEhJSk
 id: anonymous
@@ -14,5 +13,4 @@ label: 'Anonymous user'
 weight: 0
 is_admin: false
 permissions:
-  - 'access content'
   - 'use text format restricted_html'