#23286 fix(next): workspace notification banner compiles against the where/what banner (base compile red)

feat-cmux-next does not compile CmuxNextApp right now:

Sources/CmuxNextApp/Notifications/NotificationCenterService.swift:399:59: error: extra argument 'subtitle' in call

d168615bffc (cmux notify --workspace) posts a workspace notification's banner with post(..., subtitle:). 9aa00c6e20f (banners say where, who and what) had already removed that parameter: post now builds title and subtitle with NotificationBannerFormatter (title = where, subtitle = the headline and the poster's subtitle). The two landed close together and the merge broke. Fleet cmux-ci compile-check --app fails on base 66a1a077542 (job 58034821f3e8efd722a6dba8) and on 69b5399e5d3 (job 1355cfaf27521d9eac5bc916).

Fix: pass the workspace's name as workspaceName. The banner's title names the workspace and the subtitle is the headline, the same layout as a terminal's notification. WorkspaceNotificationArrivalTests expected the old layout (title = headline, subtitle = workspace); it now expects title build, subtitle Deploy done. It still checks that the banner names its workspace.

Red fix: merges once its own compile passes and an independent review passes.

No capture: the only UI effect is the title/subtitle order of a notify --workspace banner, matching every other banner.

Changelog: none

Agent session: cosmic-gray

🤖 Generated with Claude Code

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Summary by cubic

Fixes a compile error on feat-cmux-next where a workspace notification still passed subtitle: to post, but that parameter was removed when banners moved to NotificationBannerFormatter.

Passes the workspace name as workspaceName instead, so the banner's title names the workspace and the subtitle shows the headline, matching every other banner. Updates WorkspaceNotificationArrivalTests to expect that layout.