[P3] setCommonProps can strip the build version from every later event

analyticsCore.ts seeds commonProps with { version: APP_VERSION } at module load, so every event names its build whatever the entry point. But setCommonProps replaces the object wholesale, and the module-load guarantee currently survives only because the one production caller happens to re-supply the same constant: bootCommonProps takes version as a parameter and appBoot passes APP_VERSION back in.

So there are two mechanisms for one fact. Any future direct setCommonProps({...}) caller that omits version silently strips it from every subsequent event in that session, and nothing fails: the existing tripwire suite asserts the props are {} after a reset, so it would not notice.

Not a live bug. The only callers today are the boot enrichment (which carries version) and a test-only reset.

Two ways to close it, either fine:

• have setCommonProps preserve version across a replace, so the guarantee is structural rather than conventional; or
• have bootCommonProps read APP_VERSION itself instead of taking it as a parameter, removing the second source entirely.

Found by the confirming pass on #801.

Read analyticsCore.ts, especially setCommonProps and the bootCommonProps/appBoot path, then inspect the existing tripwire suite. Confirm how a replacement omitting version affects later events, choose one of the two proposed designs, and add coverage showing the build version remains guaranteed after common props are set.