Optimize custom shortcode rendering

[CySSoO]

Motivation

• Avoid loading the full set of custom shortcodes for every render when the input text does not contain shortcode-like tokens or when the current shop/language has none configured.
• Reduce DB and memory overhead by performing a lightweight pre-scan and querying only relevant shortcodes when needed.

Description

• Gate shortcode processing in src/Service/EverblockTools.php so getEverShortcodes is only invoked when textHasPotentialShortcode() returns true and a per shop/lang has_shortcodes cache indicates shortcodes exist.
• Add textHasPotentialShortcode(), extractShortcodeCandidates() and hasCustomShortcodes() helpers and change getEverShortcodes() to accept an array of candidate tokens and early-return when empty.
• Add models/EverblockShortcode.php::getShortcodesByList() which performs a targeted DbQuery for matching shortcode tokens, builds EverblockShortcode instances and caches the result instead of loading all shortcodes.
• Use EverblockCache for a EverblockTools_has_shortcodes_{shop}_{lang} presence cache and for caching getShortcodesByList() results to avoid repeated DB hits.

Testing

• No automated tests were executed for this change.

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Codex Task