formats: teach the renderer to rotate (Option A) -- and report that it does not close the title

The human chose Option A: teach sylpheed-formats own renderer to draw
rotation_deg so it and the port stay comparable and verify-screen keeps meaning
someone is wrong.

Three pieces, because rotation alone does nothing on the title. blit gains a
rotated path that draws by inverse mapping over the rotated bounding box, turning
about the pivot, whose absolute position is invariant under scale; zero rotation
keeps the original forward-mapped path byte for byte so non-rotating screens
cannot regress. compose draws a nested .rat leaf when the leaf carries geometry
the parent does not, which is the sweeps case, but not as a blanket rule since a
button s leaf duplicates its parent. And --at poses leaves at a keyframe time,
because the sweeps hold off-screen at x=1521 so a resting composite omits them.

A trap found the hard way: posing EVERYTHING at one global time is wrong, because
a top-level group s final keyframes are its exit ramp and rest() deliberately
stops before them. Posing the title at t=358 walked every parent into its exit
and drove the disagreement from 10.92 to 61.74. So at poses leaves only.

Controls: 0 and 360 degrees byte-identical to the unrotated path, 90 degrees
swaps a 10x4 to 4x10, area conserved within 15 percent, centroid stays on the
pivot. 116 lib tests pass, main_menu unchanged at 9.26.

And the verification did not show what it was meant to, which is reported rather
than buried: scanning the pose time against the title capture gives 10.73 to
11.17 against a 10.92 baseline -- flat, no minimum, best 1.7 percent. The
whole-frame mean is dominated by the tone curve, and the renderer still does not
draw ptlogo1/ptlogo2 at all, which is a far larger spatial gap than two
translucent sweeps. So rotation is correct in isolation and no screen regressed,
but whether it closes the port s 1.81 percent is not established here.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QsEPXWVaEpyfudtR6re1Pd

crates/sylpheed-cli/src/main.rs

@@ -195,6 +195,14 @@ enum ScreenCommands {
         /// `--build`**, which is why it is a flag and not the default.
         #[arg(long)]
         all: bool,
+        /// Pose every element at this KEYFRAME TIME instead of at its resting
+        /// pose (60 units = 1 second). The resting pose is the last *hold*
+        /// keyframe, which is the settled screen — wrong for anything still
+        /// moving. The title's two light sweeps hold off the right edge, so a
+        /// resting composite omits them; `--at 358` puts them where a capture
+        /// taken mid-sweep has them.
+        #[arg(long)]
+        at: Option<u32>,
     },
 }
 
@@ -353,8 +361,9 @@ async fn main() -> Result<()> {
                 black,
                 all,
                 primitives,
+                at,
             } => cmd_screen_render(
-                &pak, &output, build, focus, animated, black, all, primitives,
+                &pak, &output, build, focus, animated, black, all, primitives, at,
             ),
         },
         Commands::Save { cmd } => match cmd {
@@ -581,6 +590,7 @@ fn cmd_screen_render(
     black: bool,
     all: bool,
     primitives: bool,
+    at: Option<u32>,
 ) -> Result<()> {
     use sylpheed_formats::ui_layout::{self, ComposeOptions};
     let builds = screen_builds(pak, all)?;
@@ -599,6 +609,7 @@ fn cmd_screen_render(
                 ComposeOptions::default().backdrop
             },
             include_primitives: primitives,
+            at,
         },
         None,
     );