Update Composer and npm dependencies to latest

Composer: ~40 Symfony 7.4.x packages patched to 7.4.17, plus four
majors - doctrine/dbal 3->4, phpdocumentor/reflection-docblock 5->6,
symfony/mercure-bundle 0.3->0.5, symfony/monolog-bundle 3->4. Removed
two doctrine.yaml keys (use_savepoints, report_fields_where_declared)
that DBAL 4 deprecated in favor of fixed defaults.

npm: @symfony/webpack-encore 4->6, which required bumping its peers
webpack-cli 5->6 and sass-loader 14->16 together, plus babel-loader
9->10. Fixes the one high-severity audit finding (RCE in
serialize-javascript, via the old css-minimizer-webpack-plugin). One
moderate finding remains in webpack-notifier's dev-only notification
chain - audit's suggested fix would downgrade it, so left alone; it's
build tooling only, never shipped to users.

Verified: full test suite green, lint:container clean, both `encore
dev` and `npm run build` compile without errors, and the production
CSS output was inspected byte-for-byte to confirm the new SVG-minifier
warnings (on Bootstrap's pre-encoded icon data-URIs) don't corrupt
anything.

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

config/packages/doctrine.yaml

@@ -15,11 +15,9 @@ doctrine:
         #server_version: '16'
 
         profiling_collect_backtrace: '%kernel.debug%'
-        use_savepoints: true
     orm:
         auto_generate_proxy_classes: true
         enable_lazy_ghost_objects: true
-        report_fields_where_declared: true
         validate_xml_mapping: true
         naming_strategy: doctrine.orm.naming_strategy.underscore_number_aware
         auto_mapping: true