ref(snapshots): two small UI tweaks

[NicoHinderling]

Diff percent formatting: >= 1% shows 1 decimal (e.g. 93.5%), < 1% shows up to 4 decimals without trailing zeros (e.g. 0.0227%).

Default overlay color changed to red (5th-from-last in palette).

Legal Boilerplate

Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms.

[NicoHinderling]

• ref(snapshots): Track diff algorithm version on comparison results #112729
• ref(snapshots): Add configurable diff_threshold for snapshot comparison #112728
• ref(snapshots): Make diffing logic more strict + better handle different sized images when comparing #112632
• ref(snapshots): two small UI tweaks #112631 👈 (View in Graphite)
• master

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