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>

composer.json

@@ -7,12 +7,12 @@
         "php": ">=8.2",
         "ext-ctype": "*",
         "ext-iconv": "*",
-        "doctrine/dbal": "^3.10.5",
+        "doctrine/dbal": "^4.4.4",
         "doctrine/doctrine-bundle": "^2.18.3",
         "doctrine/doctrine-migrations-bundle": "^3.7",
         "doctrine/orm": "^3.6.7",
         "karser/karser-recaptcha3-bundle": "^0.3.0",
-        "phpdocumentor/reflection-docblock": "^5.6.7",
+        "phpdocumentor/reflection-docblock": "^6.0.3",
         "phpstan/phpdoc-parser": "^2.3.2",
         "symfony/asset": "7.4.*",
         "symfony/asset-mapper": "7.4.*",
@@ -27,9 +27,9 @@
         "symfony/intl": "7.4.*",
         "symfony/mailer": "7.4.*",
         "symfony/mailgun-mailer": "7.4.*",
-        "symfony/mercure-bundle": "^0.3.9",
+        "symfony/mercure-bundle": "^0.5.0",
         "symfony/mime": "7.4.*",
-        "symfony/monolog-bundle": "^3.11.2",
+        "symfony/monolog-bundle": "^4.0.2",
         "symfony/notifier": "7.4.*",
         "symfony/process": "7.4.*",
         "symfony/property-access": "7.4.*",