[Feature Request] Show branch + PR number in the session list; keep session titles consistent across machines

Problem

Running many parallel sessions (one git worktree per session, more than one Mac, plus remote views of the same sessions) makes the session list very hard to navigate:

1. Auto-generated titles are per-view. The same session shows different auto-names on different machines/clients, so a session referenced elsewhere ("the one working PR #109") can't be found by name in whichever sidebar you happen to be looking at.
2. Each session accumulates four unrelated handles that never match: the auto title, the worktree codename (e.g. magical-saha-72c774), the branch (e.g. claude/vigorous-shtern-bac981 — a different codename), and the PR number. None of them appear together in the picker, so mapping between them is manual archaeology.
3. Claude Code already knows the PR. Session records already carry prNumber/prState (and branch, cwd) — visible via the desktop session-management surface. The data exists; it just isn't rendered where a human navigates.

Requested

1. Render branch and open-PR number (with state) in the session picker/sidebar, next to or under the title — e.g. In-app Verify Queue for iOS mask review · verify-queue-ios-masks → PR #110 (open). Since prNumber/prState are already on the session record, this is a display-only change.
2. Make an explicitly set title (/rename) the canonical name for that session across every view — desktop app, remote control from another machine, and the --resume picker — instead of each view generating its own default. (Related bug: #75602, custom titles not shown in the --resume picker.)
3. Mechanism half tracked in #71552 (hook- or model-settable session title) — with that plus (1), teams could fully automate naming conventions like auto-appending the PR #.

Workarounds today

• /rename by hand in every session, on every machine (interactive-only).
• Repo-side tooling we built to compensate: a PostToolUse hook that posts "working PR #N: <title>" to our team coordination bus at push time, and a committed skill that answers "which session is PR #109?" by joining session list ↔ git worktree list ↔ gh pr list. It works, but this shouldn't be necessary for basic session navigation.

Environment

• Claude Code 2.1.152, desktop app on macOS (multiple Macs viewing the same projects), one git worktree per session.