fence: every runtime call is its line's site, and site 0 comes back when it returns

A block took whatever @lp_site held when it was made. Only malloc, calloc, realloc, concat, the number
texts, the float text, a substring and Text.* set one, so every other runtime helper - intern,
Text.repeat and the string builders, the Fs, Os, unicode, uuid and crypto helpers - was charged to
whichever line had allocated last (walk 9 blamed gvk_tex_storage, m4_new, kept_push$int and
survey_op_reward for intern's 16 B copies).

- Any `call ptr @lp_*` now takes a site of its own, its kind the callee's name when no better one is
  known (intern, str_repeat, fs_list, ...). What the helper makes, in however many blocks and
  through whichever helpers it calls in turn, is that line's.
- When the call returns, @lp_site goes back to site 0, now named "(runtime) (no site) unsited": a
  block made with no site of its own says so instead of borrowing the last one.
- The ECS stores' grows and a mod's registered stores - the only allocations emitted outside
  emit_bind - take a site each.

Golden alloc_fence_sites: two lines take turns keeping memory, Text.repeat and a record, every frame
judged. Each report names its own line (25 x +32 B str_repeat at :11, 25 x +16 B new Box at :12);
the toolchain before this charges 23 of the 32 B texts to the new Box line. The other fence and arena
goldens are unchanged; ludic.base's tests pass; the game's frame ratchets are 0 on main 7cb2b164.

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

examples/lang/alloc_fence_sites.ludic

@@ -0,0 +1,17 @@
+# alloc_fence_sites.ludic - 25.1: each block is charged to the line that made it. Two lines take turns
+# keeping memory, one through a runtime helper (Text.repeat) and one a record; every frame is judged
+# (R3D_ALLOC_FENCE=warn R3D_ALLOC_WARM_MAX=10) and each report names its own line - a helper once took
+# the site of whatever had allocated last
+program AllocFenceSites {
+  property Box { v: int = 0 }
+  property Keep { texts: []string = new []string, boxes: []Box = new []Box }
+  entry {
+    let k = new Keep
+    for f in 0 .. 60 {
+      if f % 2 == 0 { push(k.texts, Text.repeat("ab", 12)) }
+      else { push(k.boxes, new Box { v: f }) }
+      Mem.frame()
+    }
+    print(`texts {len(k.texts)} boxes {len(k.boxes)}`)
+  }
+}