Replace hash with contenthash.

[jameseaster]

Fix: Replace deprecated [hash] with [contenthash] in webpack output filename

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Summary

Webpack 5 deprecated the [hash] template variable for output filenames. It emits this deprecation warning when the variable is encountered:

[DEP_WEBPACK_TEMPLATE_PATH_PLUGIN_REPLACE_PATH_VARIABLES_HASH] DeprecationWarning:
[hash] is now [fullhash] (also consider using [chunkhash] or [contenthash])

The direct rename is [hash] → [fullhash], but webpack's [contenthash] might be the better choice for output filenames because it only changes when that file's content changes — giving downstream consumers better cache behavior. [fullhash] changes on every build regardless of content.

This is a patch update:

• Fixes a deprecation warning emitted by webpack 5
• Does not alter the public API of this package
• Produces the same filename structure ([name]..js), just with a more stable hash algorithm
• No consumer code changes required