fix: drop web-CSS font aliases from the Qt stylesheet

'-apple-system' is a web convention, not a real font family — Qt scans
every installed font trying to resolve it (the 'Populating font family
aliases' warning at startup). Qt already defaults to the native system
UI font on each platform, so don't name UI fonts at all. The diag
panel's 'SF Mono' (not system-installed on macOS) becomes Menlo.

bcc.py

@@ -60,7 +60,10 @@ STATUS_COLORS = {"ok": GOOD, "missing": BAD, "warn": WARN, "remote": "#60a5fa",
 STATUS_GLYPH = {"ok": "●", "missing": "●", "warn": "▲", "remote": "◆", "unknown": "○"}
 
 STYLESHEET = f"""
-* {{ font-family: -apple-system, "Segoe UI", "Inter", "DejaVu Sans", sans-serif; font-size: 13px; color: {TEXT}; }}
+/* No font-family here on purpose: Qt already uses the native system UI font
+   on every platform (San Francisco / Segoe UI / desktop default). Naming
+   web-CSS aliases like -apple-system forces a costly font-alias scan. */
+* {{ font-size: 13px; color: {TEXT}; }}
 QMainWindow, QDialog {{ background: {BG}; }}
 QLabel#h1 {{ font-size: 15px; font-weight: 600; }}
 QLabel#muted {{ color: {MUTED}; }}
@@ -103,7 +106,7 @@ QLabel#sectionDisabled {{ color: {MUTED}; font-weight: 600; font-size: 12px; pad
 QLabel#placeholder {{ color: {MUTED}; padding: 12px; background: {PANEL_2}; border: 1px dashed {BORDER}; border-radius: 8px; }}
 QTableWidget#disabledTable {{ background: #202229; }}
 QTableWidget#disabledTable::item:selected {{ background: {ACCENT}; color: #1a1205; }}
-QPlainTextEdit#diag {{ font-family: "SF Mono", "Cascadia Code", "Consolas", "DejaVu Sans Mono", monospace;
+QPlainTextEdit#diag {{ font-family: "Menlo", "Cascadia Code", "Consolas", "DejaVu Sans Mono", monospace;
     font-size: 12px; background: #16181d; border: 1px solid {BORDER}; border-radius: 8px; }}
 QFrame#diagCard {{ background: transparent; border: none; }}
 QSplitter::handle {{ background: transparent; }}