Call frame generation "Smooth motion" in user-visible text

Log lines and doc headings say "Smooth motion (frame generation)", the
player-facing name. Config key [video] frame_generation and PSX_FRAME_GEN
are unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/FRAME_GENERATION.md

@@ -1,4 +1,4 @@
-# Frame generation (`[video] frame_generation`)
+# Smooth motion (frame generation, `[video] frame_generation`)
 
 Opt-in, OpenGL with the render thread only, off by default
 (`PSX_FRAME_GEN=0/1` overrides for one run). Off, nothing in this document

docs/RENDER_THREAD.md

@@ -15,7 +15,7 @@ render_thread = true   # game.toml; PSX_RENDER_THREAD=0/1 overrides
 are also read from the player's `settings.toml` `[video]`, which wins over the
 game.toml default; the `PSX_*` env vars override both for one run and are
 never saved. The launcher shows them as Settings → Display rows (Render
-thread, Present thread, Frame generation; recomp-ui
+thread, Present thread, Smooth motion (frame generation); recomp-ui
 `RECOMP_LAUNCHER_HAS_RENDER_PIPELINE`, OpenGL only, the latter two disabled
 while Render thread is off). The pipeline starts once at boot, so a change
 from the in-game launcher is saved and applies at next launch.
@@ -176,7 +176,7 @@ resolution (below), not of this layer.
 | render passes | first `gl_renderer_pass_*` call in a frame is a sync point; the rest of that frame is synchronous. Recommended: leave `render_thread` off with the frame-rate mod |
 | frame interpolation | ineligible (held) while enabled; not started when it is on at boot |
 | OpenXR | ineligible while a session is active |
-| frame generation | `[video] frame_generation`: in-between frames drawn by the render thread from recorded lists, docs/FRAME_GENERATION.md |
+| Smooth motion (frame generation) | `[video] frame_generation`: in-between frames drawn by the render thread from recorded lists, docs/FRAME_GENERATION.md |
 | native-wide / widescreen | recorded; tags, latch and wide-surface mirror as above |
 | internal resolution changes | `gr_set_scale` and every resolution entry point are sync points; dynamic-resolution level steps are recorded (below) |
 | screenshots / debug captures | `screenshot*` sync; `present_shot` is fulfilled on the render thread |

runtime/src/debug_server.c

@@ -10419,7 +10419,7 @@ static void handle_render_thread(int id, const char *json)
     send_fmt("{\"id\":%d,\"ok\":true,%s}", id, buf[0] ? buf : "\"active\":0");
 }
 
-/* Frame generation ([video] frame_generation, docs/FRAME_GENERATION.md):
+/* Smooth motion (frame generation; [video] frame_generation, docs/FRAME_GENERATION.md):
  *   {"cmd":"frame_gen"} -> enabled, active, generated / real presents, flips,
  *   the last plan (in-between frames per game frame, display slots), costs,
  *   match counts, breaker. Not a sync point (render-thread counters, racy). */

runtime/src/main.cpp

@@ -9236,7 +9236,7 @@ static void render_thread_vblank(void) {
                          g_render_thread_frames);
             if (g_frame_generation) {
                 gl_renderer_set_frame_generation(1);
-                std::fprintf(stdout, "psxrecomp: frame generation on (render thread, "
+                std::fprintf(stdout, "psxrecomp: Smooth motion (frame generation) on (render thread, "
                              "from surplus only)\n");
             }
         } else {
@@ -9244,7 +9244,7 @@ static void render_thread_vblank(void) {
                          "(needs the OpenGL backend without netplay, frame "
                          "interpolation or a 24-bit display)\n");
             if (g_frame_generation)
-                std::fprintf(stdout, "psxrecomp: frame generation needs the render thread; off\n");
+                std::fprintf(stdout, "psxrecomp: Smooth motion (frame generation) needs the render thread; off\n");
         }
         std::fflush(stdout);
     }