fix(ui): Modal backdrop color is consistent across light/dark #29095

Job	Run time
Check Permissions	7s
Formatting \| Dedupe \| Changeset	1m 1s
Build Packages	1m 3s
Publish with pkg-pr-new	1m 2s
Unit Tests (**)	1m 51s
Unit Tests (**)	2m 7s
Static analysis	1m 8s
Integration Tests (ap-flows, chrome)	57s
Integration Tests (sessions:staging, chrome)	1m 10s
Integration Tests (sessions, chrome)	1m 11s
Integration Tests (generic, chrome)	58s
Integration Tests (localhost, chrome)	56s
Integration Tests (express, chrome)	1m 19s
Integration Tests (fastify, chrome)	1m 28s
Integration Tests (handshake:staging, chrome)	58s
Integration Tests (vue, chrome)	2m 0s
Integration Tests (nextjs, chrome, 16)	1m 29s
Integration Tests (quickstart, chrome, 15)	1m 15s
Integration Tests (quickstart, chrome, 16)	57s
Integration Tests (astro, chrome)	1m 5s
Integration Tests (cache-components, chrome, 16)	1m 47s
Integration Tests (hono, chrome)	1m 13s
Integration Tests (tanstack-react-start, chrome)	1m 30s
Integration Tests (chrome-extension, chrome)	1m 41s
Integration Tests (nuxt, chrome)	58s
Integration Tests (react-router, chrome)	57s
Integration Tests (nextjs, chrome, 15)	58s
Integration Tests (handshake, chrome)	57s
Integration Tests (machine, chrome)	58s
Integration Tests (billing, chrome)	1m 35s
Integration Tests (custom, chrome)	1m 29s
	38m 5s

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