🐛 fix(session): use secondaryLabelColor for pane options button

[kud]

Ticket

Description

The pane options button (three-dot ellipsis, iTermHamburgerButton) in the session title bar rendered inconsistently: dark/black when the window was active, gray when the window became inactive.

Root cause: menuButton_ had no contentTintColor set, so macOS fell back to controlTextColor, which adapts to window focus state and produces a jarring color shift on every activation/deactivation cycle.

Fix: set menuButton_.contentTintColor = [NSColor secondaryLabelColor] in both branches of -updateTextColor in SessionTitleView.m — the minimal-style path and the standard tab-style path. secondaryLabelColor is a semantic color that resolves to a stable, appropriately muted gray regardless of window focus, matching the visual intent of the button.

Screencast

No visual changes captured, but the bug is directly observable: open a session with the title bar visible, note the button color, click away to deactivate the iTerm2 window, then click back — the color flicker is eliminated after this fix.

How to Validate

1. Build and run iTerm2.
2. Open any session with the title bar visible.
3. Click another app to deactivate the iTerm2 window, then click back.
4. Confirm the three-dot pane options button color remains consistent (a stable muted gray) across active and inactive window states.
5. Repeat with both minimal and standard tab styles (Preferences > Appearance > Tab Style).

Developer Checklist

• Code is readable and maintainable
• Tests included and passing (if applicable) — UI color consistency; no automated test added
• PR is atomic and focused on a single bug
• Commits follow Conventional Commits