chore: sync upstream through 98beed1a22

[jln13x]

Problem

The personal fork is 300 upstream commits behind pingdotgg/t3code main. Sync through 98beed1a22 while preserving the maintained fork behavior.

Change

Merge upstream and resolve the sidebar and desktop test conflicts. Preserve worktree grouping within upstream sections, the success sound asset, desktop identity and local signing. Carry upstream projectless-thread machine labels into grouped headers, retain the browser-compatible desktop runtime name, and give the new CI artifact-transfer job the fork runner fallback. Update the fork inventory.

Server behavior, provider code, wire contracts, shared client runtime, and mobile client follow upstream. The existing fork desktop IPC branding value remains.

Scope and approval

Personal-fork maintenance requested by the fork owner, following SYNC.md. This PR targets jln13x/t3code:personal.

Verification

• vp check passed with zero errors and 909 warnings.
• vp run typecheck passed across the workspace.
• Focused sidebar grouping, drag, pointer, snooze, notification coordinator, desktop identity, profile, installation, and signing tests passed. Desktop packaging tests passed, including all 80 tests in build-desktop-artifact.test.ts.
• Electron launcher and final sidebar tests passed.
• vp run lint:mobile completed, but skipped native analysis because SwiftLint, ktlint, and detekt are unavailable on this host.
• Browser verification and before/after screenshots were not captured because browser use requires separate authorization. No installed app was replaced.

Model: gpt-6.1-sol. Harness: Codex in T3 Code.