refactor(example): restructure dxlang examples into builtin/ and tensor/

- builtin/: 30 scalar examples (call/native) — VM-only, no heap-plat/op-metal needed
- tensor/: 16 tensor examples (lifecycle/io/math/mixed/nn/call) — requires GPU backend
- Add zeros() initialization to all input tensors before compute ops
- Update parse_dx_test.go paths and compute test expectations

Author: miaobyte

example/dxlang/builtin/call/add_test.dx

@@ -0,0 +1,8 @@
+# add_test: basic element-wise addition
+def add_test(A:tensor, B:tensor) -> (C:tensor) {
+    add(A, B) -> "./C"
+}
+
+# This top-level call requires booted services (heap-plat + op-metal)
+# with tensors at /data/a and /data/b already created.
+# add_test(/data/a, /data/b) -> "/data/c"

example/dxlang/call/callee.dx example/dxlang/builtin/call/callee.dxexample/dxlang/call/callee.dx renamed to example/dxlang/builtin/call/callee.dx

@@ -2,3 +2,6 @@
 def callee(X:int, Y:int) -> (Z:int) {
     X + Y -> "./Z"
 }
+
+# Top-level call: callee(2, 3) -> "./out"
+callee(2, 3) -> "./out"

example/dxlang/call/caller.dx example/dxlang/builtin/call/caller.dxexample/dxlang/call/caller.dx renamed to example/dxlang/builtin/call/caller.dx

@@ -2,3 +2,6 @@
 def caller(A:int, B:int) -> (C:int) {
     callee(A, B) -> "./C"
 }
+
+# Top-level call: caller(2, 3) -> "./out" (calls callee internally)
+caller(2, 3) -> "./out"

example/dxlang/call/cstyle_call.dx …ample/dxlang/builtin/call/cstyle_call.dxexample/dxlang/call/cstyle_call.dx renamed to example/dxlang/builtin/call/cstyle_call.dx example/dxlang/call/cstyle_call.dx renamed to example/dxlang/builtin/call/cstyle_call.dx

@@ -2,3 +2,6 @@
 def cstyle_call(A:int, B:int) -> (C:int) {
     "./C" <- add(A, B)
 }
+
+# Top-level call: cstyle_call(2, 3) -> "./out"
+cstyle_call(2, 3) -> "./out"

example/dxlang/call/deep3.dx example/dxlang/builtin/call/deep3.dxexample/dxlang/call/deep3.dx renamed to example/dxlang/builtin/call/deep3.dx

@@ -2,3 +2,6 @@
 def deep3(X:int) -> (Y:int) {
     middle(X) -> "./Y"
 }
+
+# Top-level call: deep3(5) -> "./out" (3-level call chain)
+deep3(5) -> "./out"

example/dxlang/call/diamond.dx example/dxlang/builtin/call/diamond.dxexample/dxlang/call/diamond.dx renamed to example/dxlang/builtin/call/diamond.dx

@@ -4,3 +4,6 @@ def diamond(A:int) -> (R:int) {
     triple(A) -> "./t"
     "./d" + "./t" -> "./R"
 }
+
+# Top-level call: diamond(5) -> "./out" (double+triple→sum)
+diamond(5) -> "./out"

example/dxlang/call/double.dx example/dxlang/builtin/call/double.dxexample/dxlang/call/double.dx renamed to example/dxlang/builtin/call/double.dx

@@ -2,3 +2,6 @@
 def double(X:int) -> (Y:int) {
     X * 2 -> "./Y"
 }
+
+# Top-level call: double(5) -> "./out"
+double(5) -> "./out"

example/dxlang/call/middle.dx example/dxlang/builtin/call/middle.dxexample/dxlang/call/middle.dx renamed to example/dxlang/builtin/call/middle.dx

@@ -3,3 +3,6 @@ def middle(X:int) -> (Y:int) {
     leaf(X) -> "./tmp"
     "./tmp" + 1 -> "./Y"
 }
+
+# Top-level call: middle(5) -> "./out" (calls leaf→double internally)
+middle(5) -> "./out"

example/dxlang/call/triple.dx example/dxlang/builtin/call/triple.dxexample/dxlang/call/triple.dx renamed to example/dxlang/builtin/call/triple.dx

@@ -2,3 +2,6 @@
 def triple(X:int) -> (Y:int) {
     X * 3 -> "./Y"
 }
+
+# Top-level call: triple(5) -> "./out"
+triple(5) -> "./out"

example/dxlang/builtin/native/arith/abs.dx

@@ -0,0 +1,6 @@
+def native_abs(A:int) -> (C:int) {
+    abs(A) -> "./C"
+}
+
+# Top-level call: native_abs(-5) -> "./out"
+native_abs(-5) -> "./out"