Round-11 rebase onto main (25 commits). Reverse-merged main's new work
into the v2 cutover files: #8395 muted ordinary-tool-failure treatment
(v2-adapted workEntrySignalsSevereFailure keyed on error items), #5931
sidebar project-filter combobox + #4c51 keyboard pin/settle with their
ChatView support graph, the auto-settle-mode migration through
threadSettled/threadListV2, #8235 file/unknown attachment schemas moved
into chatAttachment.ts with nullable attachment paths, #8481 client
analytics through the v2 ws layer, #8480 OpenCode server owner wired
into the driver beside the v2 orchestration adapter, and the mobile
semantic-theme migration applied to branch-only components.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>