Replace large CX Deck badge with compact native pane titles

[lrgthu]

Dogfood UX issue from real daily use.

The CX Deck dynamic iTerm profile currently uses a large badge and enables scrollback timestamps by default. In practice this consumes too much visual space. The desired UX is closer to the earlier tmux-era pane labeling: a compact per-pane title bar showing the CX Deck display/session name while the terminal remains otherwise native iTerm2.

Proposed behavior:

• remove the CX Deck Badge Text override from the dynamic profile;
• make CX Deck scrollback timestamps default to off for fresh/default configuration while preserving an explicit cx config timestamps on|off preference;
• keep setting the native iTerm session name so iTerm's per-pane title bar can display it;
• document enabling iTerm2 Settings → Appearance → Panes → “Show per-pane title bar with split panes”;
• do not silently change the user's global iTerm appearance preference;
• do not change Codex UUID identity, zmx persistence, runtime/session lifecycle, TERM, mouse, clipboard, keybindings, or terminal output.

Acceptance:

1. CX Deck profile has no large badge.
2. Fresh/default CX Deck profile has timestamps off.
3. Existing explicit timestamp preference remains honored.
4. Rename/presentation continues to update the native session name.
5. Tests cover profile payload/default preference and no runtime semantics change.
6. Full public CI passes.

Reference: iTerm2 documents that the Session Title is what appears in split-pane title bars, and the per-pane title bar is controlled by the user's iTerm appearance preference.