fix(templates): respect reverse-proxy path prefix in hardcoded JS/URLs

[jeromelefeuvre]

Summary

When Prismarr is served behind a reverse proxy that strips a path prefix (e.g. Traefik routing https://host/prismarr/... to the container root, with X-Forwarded-Prefix: /prismarr forwarded), server-generated URLs are already prefix-safe via instance_path() / path() (which go through the Symfony router, itself driven by Request::getBasePath() — already trusted via trusted_headers: [..., x-forwarded-prefix] in config/packages/framework.yaml).

However, ~276 places across 67 Twig templates build absolute paths as raw string literals inside inline <script> blocks or href/action attributes (fetch('/medias/' + slug + ...), href="/jellyseerr/...", etc.). These literals ignore the prefix entirely, since X-Forwarded-Prefix only affects server-side URL generation, not raw JS strings.

Fix

• Standard case (raw text inside a <script> block or HTML attribute): prefix the literal with {{ app.request.getBasePath() }}.
• Edge case (~9 occurrences already inside an open Twig expression, e.g. {% include ... with { save_url_edit: ... } %} or a ternary): use the Twig concat operator app.request.getBasePath() ~ '...' instead, since {{ }} doesn't interpolate inside an already-parsed Twig expression.
• One occurrence (/api/health/services) was switched to the named route via {{ path('api_health_services') }} instead, which is cleaner and needed no raw-path handling.

Request::getBasePath() already reflects X-Forwarded-Prefix (Symfony 5.3+), so this resolves to /prismarr behind the proxy and '' on a root deployment — no extra config needed.

Affected roots: /medias, /decouverte, /jellyseerr, /prowlarr, /setup.

Test plan

• make lint-twig (php bin/console lint:twig templates) — all 149 Twig files pass syntax validation
• Swept the repo for any remaining hardcoded absolute paths on the 5 affected roots — none left
• Manually verified each of the 9 "already inside a Twig expression" cases renders correctly with ~ instead of {{ }}