internal: add CSP header to files in `/media` #25826

Job	Run time
lint (bandit)	2m 2s
test-migrations	2m 44s
lint (black)	1m 53s
lint (codespell)	1m 42s
lint (pending-migrations)	1m 50s
lint (ruff)	2m 19s
test-unittest - PostgreSQL 15-alpine	17m 48s
test-unittest - PostgreSQL 16-alpine	17m 45s
test-integration	5m 39s
test-e2e (proxy)	8m 40s
test-e2e (oauth)	7m 54s
test-migrations-from-stable - PostgreSQL 15-alpine	18m 35s
test-e2e (oauth-oidc)	6m 12s
test-migrations-from-stable - PostgreSQL 16-alpine	18m 4s
test-e2e (saml)	6m 28s
test-e2e (ldap)	10m 47s
test-e2e (radius)	5m 37s
test-e2e (scim)	4m 11s
test-e2e (flows)	5m 25s
ci-core-mark	1s
build (amd64)	11m 12s
build (arm64)	10m 9s
pr-comment	8s
	2h 47m 5s

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