Console pulse: one-third speed (150ms frames), 256-ramp untouched

YuKu: 'slow the flicker a bit (half or one-third speed)'. The 16-colour
blue<->grey pulse now ticks at 150ms (600ms full cycle, calm); the
256-colour terminal breathe keeps its 50ms deep ramp. Per-depth tick
variable; same in the vendored helper.

Rate proven by pty trace: 8 frames in a 1.2s transaction = 150ms
exactly. (Frame-counting via grep -c undercounts — \r overwrites
collapse frames onto one line; count matches, not lines.)

lib/common.sh

@@ -117,6 +117,12 @@ ui_quiet_run() {
     # "solid blue, no breathing" on the console). Cap to the 16-color path.
     case "${TERM:-}" in linux*|console*) depth=16 ;; esac
 
+    # Per-depth frame interval: the console colour-pulse runs slower (a fast
+    # blue/grey flip reads as flicker — YuKu asked for half-to-third speed);
+    # the 256-colour breathe ramp keeps its 50ms.
+    local tick=0.05
+    (( depth == 16 )) && tick=0.15
+
     local -a bg=()
     case "$depth" in
         # Deep-amplitude breathe: dark navy (17) to BRIGHT blue (45). Adjacent
@@ -152,7 +158,7 @@ ui_quiet_run() {
             fi
         fi
         f=$(( f + 1 ))
-        sleep 0.05
+        sleep "$tick"
     done
 
     local rc=0