Script v2: Experiment with engagement metrics measuring client-side

[apata]

Changes

Please describe the changes made in the pull request here.

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Tests

• Automated tests have been added
• This PR does not require tests

Changelog

• Entry has been added to changelog
• This PR does not make a user-facing change

Documentation

• Docs have been updated
• This change does not need a documentation update

Dark mode

• The UI has been tested both in dark and light mode
• This PR does not change the UI

[github-actions]

Preview environment👷🏼‍♀️🏗️
PR-5731

[github-actions]

Analyzed 1026 tracker script variants for size changes.
The following tables summarize the results, with comparison with the baseline version in parentheses.

Main variants:

	Brotli	Gzip	Uncompressed
npm_package/plausible.js (new variant)	2408B	2756B	6688B
plausible-web.js	2239B (+24B / +1.1%)	2563B (+25B / +1%)	6180B (+90B / +1.5%)

Important legacy variants:

	Brotli	Gzip	Uncompressed
plausible.js	1171B (+25B / +2.2%)	1366B (+26B / +1.9%)	3095B (+90B / +3%)
plausible.hash.js	1133B (+18B / +1.6%)	1331B (+25B / +1.9%)	2974B (+90B / +3.1%)
plausible.pageview-props.tagged-events.js	1702B (+15B / +0.9%)	1994B (+29B / +1.5%)	4626B (+90B / +2%)
plausible.file-downloads.hash.pageview-props.revenue.js	1567B (+25B / +1.6%)	1851B (+26B / +1.4%)	4022B (+90B / +2.3%)
plausible.compat.exclusions.file-downloads.outbound-links.pageview-props.revenue.tagged-events.js	2302B (+19B / +0.8%)	2721B (+20B / +0.7%)	6264B (+90B / +1.5%)

Summary:

	Brotli	Gzip	Uncompressed
Largest variant (plausible.compat.exclusions.file-downloads.outbound-links.pageview-props.revenue.tagged-events.js)	2302B (+19B / +0.8%)	2721B (+20B / +0.7%)	6264B (+90B / +1.5%)
Max change (plausible.local.revenue.js)	1058B (+33B / +3.2%)	1257B (+26B / +2.1%)	2842B (+90B / +3.3%)
Min change (plausible.exclusions.file-downloads.outbound-links.pageview-props.revenue.js)	1764B (+8B / +0.5%)	2097B (+25B / +1.2%)	4599B (+90B / +2%)
Median change	1671.5B (+24B / +1.5%)	1980B (+26B / +1.4%)	4368B (+90B / +2.1%)

In total, 1025 variants brotli size increased and 0 variants brotli size decreased.