fix(sessions): recognise iTermServer daemon so focus works

[StuBehan]

Problem

Pressing ⏎ Focus on the Sessions tab did nothing — it never brought the session's window/tab to the front. The tab also showed reduced session data (no terminal name, tab label, or accent colour) for iTerm2 sessions.

Root cause

iTerm2 3.5+ runs each session under a detached iTermServer-<version> daemon (session restoration) that is parented to launchd, not under the iTerm2 app — and the app itself isn't in the process parent chain to walk up to.

SessionStore.walkParentChain only did exact matches against "iTerm2"/"iTerm", so the version-suffixed daemon name (e.g. iTermServer-3.6.11) never matched. terminalApp stayed nil, which:

• made focusSelectedSession() bail at its bundleID(for:) guard → focus was a silent no-op, and
• caused ITerm2Integration.enrich (which filters on terminalApp.contains("iTerm")) to skip enrichment → no tabId / tabName / colour.

Changes

• SessionStore — new canonicalTerminalApp(_:) normalises the iTermServer-* daemon back to the canonical "iTerm2", so every downstream check (bundleID lookup, iTerm enrichment, focus) recognises it. (the unblocker)
• Panel.focusSelectedSession() — route session.tabId to the activation param the terminal actually reads: ipcHook for VSCode/Cursor/Antigravity (VSCODE_IPC_HOOK_CLI), sessionID for iTerm2 (its session GUID). Previously tabId was dropped entirely, so focus landed on whatever window the app last had frontmost.
• AppActivator.focusIterm2Session — match iTerm2 sessions on unique id (the persistent GUID our enrichment and ITERM_SESSION_ID both carry), with id kept as a fallback.

Testing

• swiftc -typecheck panel/*.swift shared/*.swift — clean.
• Verified live: with the daemon recognised, iTerm2 sessions show their terminal/tab metadata again and ⏎ jumps to the exact pane.

Follow-ups (not in this PR)

• notify.sh:walk_session_chain has the same iTermServer gap on the nudge focus path (partly masked by TERM_PROGRAM/ITERM_SESSION_ID).
• Zed is recognised by notify.sh but not by the Sessions tab, and isn't focusable in AppActivator at all.

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