chore: merge upstream nightly v0.0.43-nightly.20260926.2318 into custom-nightly

[chamaquita-d3]

Fixes #18

Merging upstream nightly v0.0.43-nightly.20260926.2318 into custom-nightly stopped on conflicts in five files. This PR is that merge (a real merge commit, so the tag stays an ancestor) with every conflicted hunk resolved. Everything git merged cleanly is left as it was.

File:lines	Class	custom-nightly	Upstream	Kept	Why
apps/web/src/components/NoProjectsHero.tsx:5-6	disjoint	imports CustomBackground for the background picture	imports isElectron for the new desktop titlebar strip (pingdotgg#13713)	both imports	Each import is used by its own side's change in the body, which merged cleanly
apps/web/src/components/chat/ComposerSurface.tsx:16-19	disjoint	composer glass fill reads the fork's shared --glass-surface token (drops the per-theme --card/--surface-raised overrides)	max-w-3xl → max-w-(--chat-max-width) for the new chat width setting (pingdotgg#11594)	fork's lines, with upstream's max-w-(--chat-max-width)	The two sides edited different classes in the same lines
apps/web/src/components/chat/MessagesTimeline.tsx:1256	disjoint	row root overflow-x-clip → [contain:inline-size], so reply bubble blur and shadows are not clipped	max-w-3xl → max-w-(--chat-max-width) (pingdotgg#11594)	max-w-(--chat-max-width) [contain:inline-size]	Different classes on the same line; both behaviors are kept
apps/web/src/components/settings/SettingsPanels.tsx:657-659	disjoint	restore-defaults dirty check watches activeCustomBackgroundId, customBackgroundEnabled	watches chatWidth (pingdotgg#11594)	all three	Independent settings in the same list
apps/web/src/routes/__root.tsx:32-33	disjoint	imports MascotMoodCoordinator (Dock cat)	imports QueuedMessageSender (pingdotgg#13764)	both imports	Different root coordinators
apps/web/src/routes/__root.tsx:235-236	disjoint	mounts <MascotMoodCoordinator />	mounts <QueuedMessageSender />	both, in that order	Both are headless coordinators, so order does not matter

pnpm-lock.yaml merged without conflicts. As the task asks, I took upstream's copy and regenerated it with pnpm install --lockfile-only (pnpm 11.10.0) against the merged manifests.

No checks were run locally. Fork CI runs them on this PR.

Resolved by Claude Opus 5.5 in Claude Code.

Follow-up: CI timeout

Upstream's new packages/client-runtime/src/platform/persistence.test.ts samples 2000 generated shells. That took 6.3s on the fork's ubuntu-latest runners and exceeded vitest's default 5s timeout; upstream runs on 8-vCPU Blacksmith runners. The fork doesn't change these schemas. The test now has a 30s timeout, and its assertions are unchanged.

🤖 Generated with Claude Code