GUI: Insert-only close, freeze mouse look at the source

Feedback pass:

- Insert now toggles the GUI; the old text tree moved to F1.
- Remove the title-bar X. Insert is the only close path; Esc only cancels
  bind capture.
- Discard accumulated mouse deltas in CInput::CreateMove before the game can
  apply them (CInput::ClearStates), so the camera no longer moves for a frame
  and snaps back. Also skip ExtraMouseSample and zero relative mouse state
  while the GUI is open.
- Strip attack/use/impulse/weapon selection from the command while open;
  keep jump, duck and walk. Skip combat command edits (spread seed) too.
- Widen System page buttons so "Reload config" and "Reset defaults" fit.
- Update CONTEXT/ADR for the Insert-only close behavior.

1 files changed, 5 insertions, 4 deletions

diff --git a/src/menu.cpp b/src/menu.cpp
index 56fe6fa..a0cf323 100644
--- a/src/menu.cpp
+++ b/src/menu.cpp
@@ -467,7 +467,8 @@ static void config_load() {
 // ---------------------------------------------------------------------------
 
 // SDL scancodes for navigation keys (matches the game's scancode set)
-static constexpr int SCAN_INSERT = 73;
+static constexpr int SCAN_INSERT = 73; // reserved for the GUI
+static constexpr int SCAN_TEXT_MENU = 58; // F1 preview key for the old tree
 static constexpr int SCAN_UP = 82;    // these are SDL scancodes
 static constexpr int SCAN_DOWN = 81;
 static constexpr int SCAN_LEFT = 80;
@@ -637,7 +638,7 @@ static void menu_handle_input() {
   // SDL state can be sampled several times per rendered frame (both ISurface
   // hooks call outer_draw). Use a physical-key latch instead of the one-poll
   // edge so one press cannot open and close the menu in the same frame.
-  bool insert_down = key_held(SCAN_INSERT);
+  bool insert_down = key_held(SCAN_TEXT_MENU);
   bool insert_edge = insert_down && !g_insert_latch;
   if (insert_down)
     g_insert_latch = true;
@@ -662,8 +663,8 @@ static void menu_handle_input() {
     for (int i = 0; i < MOUSE_BASE + 5; i++) {
       if (!g_key_down[i])
         continue;
-      if (i == SCAN_INSERT || i == SCAN_UP || i == SCAN_DOWN ||
-          i == SCAN_LEFT || i == SCAN_RIGHT) {
+      if (i == SCAN_INSERT || i == SCAN_TEXT_MENU || i == SCAN_UP ||
+          i == SCAN_DOWN || i == SCAN_LEFT || i == SCAN_RIGHT) {
         g_bind_mode = false;
         return; // cancel bind select
       }