Fix plus decoding in URL search hashes

[puneetdixit200]

Summary

• add a hash-fragment decoder that preserves literal + characters
• use it for URL search hash parsing in both Search and SearchScope
• cover scoped C++ URL searches and encoded literal plus queries with a focused Node test

Fixes #2463.

Tests

• node --test test/assets/search_hash_test.js
• node --check assets/javascripts/lib/util.js && node --check assets/javascripts/views/search/search.js && node --check assets/javascripts/views/search/search_scope.js && node --check test/assets/search_hash_test.js
• git diff --check

Not run locally: bundle exec rake because this checkout requires Ruby 4.0.5 and Bundler 4.0.12, while this machine only has system Ruby 2.6.10 and no matching Bundler.

[Copilot]

Pull request overview

This PR fixes URL hash-based searches where literal + characters (e.g., c++) were incorrectly treated as spaces during decoding, which broke scoped searches like #q=c++%20std::min.

Changes:

• Added $.urlDecodeFragment to decode hash fragments without converting + into spaces.
• Updated Search and SearchScope hash parsing to use $.urlDecodeFragment.
• Added a focused Node test covering scoped C++ URL searches and encoded literal plus queries.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
assets/javascripts/lib/util.js	Adds $.urlDecodeFragment for fragment decoding that preserves literal +.
assets/javascripts/views/search/search.js	Switches hash decoding to $.urlDecodeFragment when extracting the query.
assets/javascripts/views/search/search_scope.js	Switches hash decoding to $.urlDecodeFragment for scoped hash extraction and rewrite.
test/assets/search_hash_test.js	Adds a Node VM-based test covering the C++ scoped query regression and %2B literal plus decoding.

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[simon04]

Thank you!