fix: constellation preset swap no longer reads falsely dirty

The Constellation preset sets constellation_restamp_floor, but the field
has no ProfileOverrides counterpart (capture can't read it back) and is
not runtime-editable. Live capture projected it to its default while the
preset resolved to its set value, so the dirty guard saw a phantom diff
and prompted to discard when swapping away from constellations. Normalize
it on both sides in project(), matching trail_modulation/respawn_config.

Author: tamirelazar

src/profile_overrides.rs

@@ -891,6 +891,13 @@ pub(crate) fn project(ov: &ProfileOverrides) -> Result<Canonical, String> {
     // carry None while capture carries Some.
     sim.respawn_config = Default::default();
 
+    // `constellation_restamp_floor` is set by the Constellation preset's sim-default
+    // layer, but it has no `ProfileOverrides` field (capture can't read it back) and
+    // is not runtime-editable. Capture therefore projects it to its default while a
+    // clean Constellation swap resolves it to the preset value, making the swap read
+    // falsely dirty. Normalize on BOTH sides so the guard stays blind to it.
+    sim.constellation_restamp_floor = Default::default();
+
     // Reproduce apply_color_aa_all priority EXACTLY ([P1]):
     //   1. full per-charset array if color_aa_all present,
     //   2. else the FULLY RESOLVED color_aa on the RESOLVED charset's slot over defaults.

src/terminal/state.rs

@@ -2849,6 +2849,21 @@ mod tests {
         );
     }
 
+    /// Repro: a freshly-applied Constellation preset must NOT read dirty.
+    #[test]
+    fn clean_constellation_swap_is_not_dirty() {
+        use crate::profile_overrides::ProfileOverrides;
+        let ov = ProfileOverrides {
+            preset: Some(Preset::Constellation),
+            ..Default::default()
+        };
+        let (rs, sim) = clean_session(ov);
+        assert!(
+            !rs.is_dirty(&sim, rs.live_palette.clone(), rs.live_charset.clone()),
+            "a freshly-applied Constellation preset must not read dirty"
+        );
+    }
+
     /// CLEAN `--color-aa subtle` session: the source carries a scalar `color_aa`,
     /// live capture re-captures it, and project() must reproduce apply_color_aa_all
     /// semantics (scalar on the RESOLVED charset slot over defaults) so the two