Turn object snap on by default

The running snap set was already seeded with endpoint, midpoint,
centre, node, quadrant, intersection and nearest, but the master
suppress bit was set, so none of them did anything until the user
found the status-bar pill. Snapping is what makes a drawing close
rather than nearly close; it should be live from the first click.

Only fresh configs change. A stored settings.json keeps whatever
osmode it already holds, and a legacy file carrying its own $OSMODE
still overrides on open.

src/app/settings.rs

@@ -646,8 +646,10 @@ impl Default for UserSettings {
             literal_spaces: false,
             command_history_height: crate::ui::command_line::HISTORY_HEIGHT_DEFAULT,
             // Snapper::default(): END|MID|CEN|NODE|QUAD|INT|NEA (575), master
-            // off (suppress bit 16384).
-            osmode: 575 | OSMODE_SUPPRESS,
+            // on. Object snap is a drafting aid users expect to be live from
+            // the first click; the suppress bit (16384) is left for the user
+            // to set via the status-bar pill or OSNAP.
+            osmode: 575,
             texteditmode: false,
             quick_dimension_snap_priority: 0,
             dimension_continue_mode: 1,

src/snap.rs

@@ -278,7 +278,7 @@ impl Default for Snapper {
         // would catch nearly every cursor position, masking the discrete
         // vertex/edge/face snaps. Opt in via the 3D Object Snap tab.
         Self {
-            snap_enabled: false,
+            snap_enabled: true,
             enabled,
             snap3d_enabled: true,
             enabled3d,