Improve toolbox search indexing for translated block labels

[tracygardner]

Motivation

• Make toolbox search return results based on the full visible block label in the active language rather than only block type names and dropdown/field snippets.
• Ensure indexed text reflects runtime language changes so search results remain localized.
• Preserve and extend existing keyword and field/dropdown indexing to keep search robust.

Description

• Added a custom index builder in main/blocklyinit.js that constructs a searchable text for each toolbox block by collecting type, keyword (including blockInfo.full.keyword), field text, dropdown options, and the block’s rendered label via block.toString() with a translated message0 fallback using Blockly.utils.replaceMessageReferences and translate().
• Indexing uses a temporary Blockly.Workspace which is disposed after building the index, and the category’s blockSearcher.indexBlocks is replaced with a rebuildSearchIndex function so the index can be rebuilt on demand; the search category is exposed at workspace.flockSearchCategory.
• Hooked into the language-change flow in main/translation.js to call workspace.flockSearchCategory.blockSearcher.indexBlocks() after setLanguage refreshes toolbox and blocks so the search index is retranslated to the active language.

Testing

• No automated tests were run for these changes.

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Codex Task