feat(tui)!: consolidate terminal UI improvements

packages/ui/tui/tests/snapshots/session-reference.expected.txt

@@ -4,15 +4,15 @@ title "DSH session reference"
 cursor hidden column=7 viewportRow=14 bufferRow=14
 buffer
 0| " DEEPSEEK HARNESS"
-  style 1-8 fg=bright-blue bold
+  style 1-8 fg=bright-magenta bold
   style 10-16 bold
 1| " Session reference snapshot."
-  style 1-27 fg=bright-black
+  style 1-27 dim
 2| " target-session"
   style 1-14 dim
 3| <blank>
 4| "You                                                                                             "
-  style 0-2 fg=bright-blue bold underline
+  style 0-2 fg=bright-magenta bold underline
 5| "Use @Source session                                                                             "
 6| <blank>
 7| "Referenced sessions · Source session (source-session)                                           "
@@ -25,11 +25,11 @@ buffer
   style 0-46 dim
 12| <blank>
 13| "/workspace/project  mock  ↑0 ↓0"
-  style 0-17 fg=bright-blue bold
-  style 20-23 fg=bright-black
-  style 26-30 fg=bright-black
+  style 0-17 fg=bright-magenta bold
+  style 20-23 dim
+  style 26-30 dim
 14| " dsh ◍                                                                                          "
-  style 1-3 fg=bright-blue bold
-  style 5-6 fg=bright-black
+  style 1-3 fg=bright-magenta bold
+  style 5-6 dim
   style 7-7 inverse
 15-23| <blank>