[Shop] Stop decoding entities in rendered content elements output

[JustMordeckai]

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
Related tickets	fixes #202
License	MIT

ContentElementRendererStrategy ran html_entity_decode(ENT_QUOTES) over the rendered HTML of every content element. The decode compensated Twig's auto-escaping for the four elements that emit pre-rendered HTML through a plain {{ variable }}, but it also inverted the escaping of every plain-text field (markup typed in a heading landed unescaped in the page) and corrupted attributes legitimately carrying entities (data-live-props-value="{"... gets cut at the first decoded quote, killing Symfony UX Live Components inside products grids). Details and reproduction in #202.

This PR makes the strategy emit the rendered HTML untouched, and moves the unescaping where it belongs: a local |raw in the four templates whose variable holds pre-rendered HTML (textarea, single_media, multiple_media, pages_collection). For those four elements the output is unchanged: their escape-then-decode round trip was lossless, |raw just short-circuits it. Every other element now keeps Twig's escaping. Content that relied on the accidental unescaping (raw HTML typed into plain-text fields such as headings) now displays literally, which is the escaping contract those fields were meant to have.

Tests: the two strategy tests that asserted the decoding are updated, and a new one pins the pass-through behaviour (escaped user text stays escaped, entity-carrying attributes survive). Full tests/Unit suite green (183 tests, 457 assertions).

Deliberately out of scope: Twig/Runtime/RenderContentRuntime applies the same decode, but to stored content rather than template output, so it deserves its own analysis. Happy to follow up on it separately.