feat: adopt auto-settle-on-merge, wake icon alignment, and stage artwork

[rynfar]

Adopts three upstream changes from the 2026-08-14 review: a real user-facing setting, a sidebar alignment fix, and the stage artwork palette rework.

What's here

• #5880 — a setting to stop threads auto-settling when their pull request merges. Adds sidebarAutoSettleOnMerge to the client settings contract, defaulting to true, so today's behaviour is unchanged unless a user opts out. Closed pull requests still always settle; only the merge case becomes configurable. Upstream already covered every surface — contracts, client-runtime, web settings (row, search entry, restore-defaults) and mobile (settings screen, thread list, preferences). Timely now that we've just adopted the pull request surfaces, which make merge-settle much more visible.
• #6215 — the snoozed-thread wake icon sits on the row's optical centre. Two lines of generic geometry.
• #6535 — stage artwork palette rework. Replaces the derived night palette with explicit values, adds glow and sparkle pigments, and scopes the old color-mix derivation to the t3-chat, ocean and iris themes. All three theme ids still exist in Pylon, and the clean cherry-pick confirms we had not diverged here.

Pylon adaptations

#6535 arrived with the comment "Keep the original T3 Code artwork palettes as the defaults". Rebranded to describe them as inherited, following the O11 precedent.

Verification

• vp test run over the four touched test files: 264 passed.
• Typecheck on @t3tools/web, @t3tools/contracts, @t3tools/client-runtime, @t3tools/mobile, @t3tools/desktop: no errors. (Filters confirmed to match real packages rather than silently passing.)
• vp lint over the changed files: clean.

Before / after on the stage backdrop

Captured on one dev server against a seeded copy of real data, swapping only index.css over HMR so the data and layout are identical between shots. The affected region is the sidebar header behind the Pylon mark.

The change is subtle at normal size — the night palette gains a slightly brighter, better-defined blue with an explicit glow, where the derived version was flatter. Judge it yourself before merging; I have no strong view, and it is easy to drop this one commit if you dislike it.

Measured variable delta on the default dark theme:

Variable	Before	After
--stage-night-top	color-mix(… 38%, …) derived	oklch(0.283792 0.117327 297.201)
--stage-night-highlight	inherited from --stage-art-highlight	oklch(0.707246 0.157418 252.091)
--stage-night-glow-highlight	(did not exist)	oklch(0.553749 0.176543 271.958)
--stage-night-sparkle	(did not exist)	oklch(0.880867 0.057747 269.011)

Model: Claude Opus 5. Harness: Claude Code.

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[github-actions]

Thread transfer impact

⚠️ The latest CI run did not produce a thread transfer result for 4dbf337.

This comment will update automatically after the next completed run.