[Web] Add log-level attribute for console verbosity

[markmur]

What

Replaces the boolean debug attribute/property with a log-level attribute and logLevel property carrying an ordered LogLevel enum: debug, warn, error, none.

• Levels form a threshold: debug is the most verbose, none silences everything; selecting a level emits that level and every more-severe level.
• Defaults to error. This intentionally diverges from the other platforms (which default to warn): web logs go to the browser console, which is inherently more public than a native device log, so we default to the quietest level that still surfaces failures during integration.
• Console output is routed through a small Logger utility gated by the current level, replacing the ad-hoc debug-gated warnings.

Threshold

log-level	console.debug	console.warn	console.error
debug	✅	✅	✅
warn	–	✅	✅
error (default)	–	–	✅
none	–	–	–

Usage

<!-- attribute -->
<shopify-checkout log-level="debug" src="..."></shopify-checkout>

// property
const checkout = document.querySelector('shopify-checkout');
checkout.logLevel = 'error'; // errors only
checkout.logLevel = 'none';  // silence everything

Migration

- <shopify-checkout debug src="..."></shopify-checkout>
+ <shopify-checkout log-level="debug" src="..."></shopify-checkout>

[markmur]

• [React Native] Canonicalize LogLevel to debug/warn/error/none #444
• [Web] Add log-level attribute for console verbosity #443 👈 (View in Graphite)
• [Android] Add NONE log level #442
• [Swift] Canonicalize LogLevel to debug/warn/error/none #441
• [Kotlin] Move Client to protocol #438
• Add decode logging parity for Web + Swift + Android #437
• main

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[github-actions]

Web — Coverage Report

Lines	Statements	Branches	Functions
	98.8% (248/251)	85.49% (112/131)	98.57% (69/70)

[github-actions]

Package Size

Platform	Artifact	Base	Head	Delta
Web	npm tarball	63.8 KiB	65.5 KiB	+1.7 KiB

Web file breakdown

File	Base	Head	Delta
dist/index.js.map	182.0 KiB	184.1 KiB	+2.1 KiB
dist/index.d.ts	41.2 KiB	41.9 KiB	+665 B
dist/custom-elements.json	36.0 KiB	40.1 KiB	+4.2 KiB
dist/index.js	29.2 KiB	29.6 KiB	+387 B
README.md	17.2 KiB	17.8 KiB	+634 B
package.json	2.8 KiB	2.8 KiB	0 B
LICENSE	1.1 KiB	1.1 KiB	0 B

Measured from the PR base SHA and PR head SHA. The file breakdown shows uncompressed sizes within each package artifact, so individual files do not sum to the compressed artifact total. This comment reports package artifact sizes only; it is not a final app binary-size report.