feat(ludic.tracks): prints, their age and reading them as a mechanic package

A ring of prints per kind; a port for the trip's time, the reader's tier, a
bearing in words and a hook the game draws each print through. A read is a
TrackRead fact on tracks_reads() every time and a count the first time; other
sign is told with tracks_note. The count and last bearing are its save section.

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

packages/ludic.tracks/leave.ludic

@@ -0,0 +1,37 @@
+# leave.ludic - a print put down. Each kind is a ring: past its cap the oldest is written over, and
+# a slot written over is a new print, unread
+function tk_ok(kind: int) -> bool { return tk_ring != null and kind >= 0 and kind < tk_kinds }
+
+# a print made at `made` game hours (another machine's, arriving here); the ring index, or -1
+export function tracks_leave_at(kind: int, x: float, z: float, yaw: float, sp: int, legend: bool, made: float) -> int {
+  if not tk_ok(kind) { return -1 }
+  var i = tk_next[kind]
+  if tk_count[kind] < tk_cap {
+    i = tk_count[kind]
+    tk_count[kind] = tk_count[kind] + 1
+  }
+  tk_next[kind] = (i + 1) % tk_cap
+  let t = tk_ring[kind * tk_cap + i]
+  t.x = x
+  t.z = z
+  t.yaw = yaw
+  t.sp = sp
+  t.legend = legend
+  t.made = made
+  t.read = false
+  if tk_world != null and tk_world.placed != null { tk_world.placed(kind, i) }
+  return i
+}
+
+export function tracks_leave(kind: int, x: float, z: float, yaw: float, sp: int, legend: bool) -> int {
+  return tracks_leave_at(kind, x, z, yaw, sp, legend, tk_now())
+}
+
+# the ground forgets every print (a new world)
+export function tracks_clear() -> void {
+  if tk_ring == null { return }
+  for k in 0 .. tk_kinds {
+    tk_count[k] = 0
+    tk_next[k] = 0
+  }
+}