GeezerVison

Several AgentsPage settings views, header buttons and helpers declared props or parameters optional, but every production caller passes them. AgentSettingsCompactionPage always passes an array for models (from useOrganizationChatModels) plus a compactionModelIDByOrganization map. AgentSettingsUserAgentsPage always passes onRetryOverrides and isRetryingOverrides, and AgentSettingsPersonalSkillsPage always passes isExportingAll. AgentCreatePage always passes enabled/onToggle to ChimeButton and webPush/onToggle to WebPushButton. AgentCreateForm always passes onChange to CompactOrgSelector, and AgentChatInput always passes unsupportedProviderNames to AgentSetupNotice (it defaults the value to [] itself). AgentsPageLayout always passes onToggleSearch. getUsableDefaultModelIDForOrganization, resolveCompactionThreshold, getModelDisplayName and changeColor are always called with non-null values, and UsageRingProgress always gets severity.

These are now required, and the dead defaults, ?./&& guards and fallbacks are gone. ChimeButton and WebPushButton are now controlled-only: the internal chime state, the internal useWebpushNotifications() call and the fallback subscribe/unsubscribe/toast branch are removed. getModelDisplayName keeps isUnsetModelRef, since that also treats "" and the nil UUID as unset. The stories now pass the required args. ChimeButton.stories swaps its click-to-toggle story for an explicit Enabled story, so the two visual states stay covered. Left optional on purpose: aiGatewayDisabled and CompactIntegerField.error/disabled (skip list), and ChatsSidebar.canManageAgentSettings, which is narrowed in #29889.

Part of the AgentsPage nullability cleanup; see #29888 for the methodology. Dead slots for this cluster: 20 before, 1 after (the remaining one is canManageAgentSettings, owned by #29889).

This PR was generated by Coder Agents on behalf of @DanielleMaywood.