test: group examples into per-category folders

Move examples/*.sx and their expected/ snapshots into per-category
subfolders (examples/<category>/...). Folder = leading filename token,
with ffi-objc/ffi-jni kept whole; filenames are unchanged. The corpus
runner and LSP sweep now discover each category's expected/ dir, while
issues/ stays flat. Example 1058's repo-root-relative companion import
is made file-relative. Path strings embedded in 164 snapshots were
regenerated (path-only changes). Test-layout docs in CLAUDE.md updated.

examples/closures/expected/0300-closures-lambda.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0300-closures-lambda.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0300-closures-lambda.stdout

@@ -0,0 +1 @@
+-3

examples/closures/expected/0301-closures-fn-pointers.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0301-closures-fn-pointers.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0301-closures-fn-pointers.stdout

@@ -0,0 +1,4 @@
+fp(3,4) = 7
+fp(3,4) = 12
+apply(add,5,6) = 11
+apply(mul,5,6) = 30

examples/closures/expected/0302-closures-closures.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0302-closures-closures.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0302-closures-closures.stdout

@@ -0,0 +1,13 @@
+basic: 142
+snapshot: 15
+clamp: 50 0 100
+[INFO] system ready
+factory: 105 110
+auto-promote: 21
+hof: 40
+reduce: 15
+compose: 30
+multi: 105 500
+widget: slider = 42
+widget: no handler
+=== DONE ===

examples/closures/expected/0303-closures-closure-returning-protocol.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0303-closures-closure-returning-protocol.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0303-closures-closure-returning-protocol.stdout

@@ -0,0 +1,2 @@
+direct call works
+closure call works

examples/closures/expected/0304-closures-enum-arg-through-closure-field.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0304-closures-enum-arg-through-closure-field.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0304-closures-enum-arg-through-closure-field.stdout

@@ -0,0 +1,2 @@
+cl f = 1
+cl f = 0

examples/closures/expected/0305-closures-closure-field-call-via-self-ptr.exit

@@ -0,0 +1 @@
+2

examples/closures/expected/0305-closures-closure-field-call-via-self-ptr.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0305-closures-closure-field-call-via-self-ptr.stdout

@@ -0,0 +1 @@
+

examples/closures/expected/0306-closures-closure-env-routes-through-context-allocator.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0306-closures-closure-env-routes-through-context-allocator.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0306-closures-closure-env-routes-through-context-allocator.stdout

@@ -0,0 +1 @@
+Tracer.count = 1

examples/closures/expected/0307-closures-closure-contextual-params.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0307-closures-closure-contextual-params.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0307-closures-closure-contextual-params.stdout

@@ -0,0 +1,3 @@
+cb=15
+r=15
+q=6

examples/closures/expected/0308-closures-arrow-inferred-return.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0308-closures-arrow-inferred-return.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0308-closures-arrow-inferred-return.stdout

@@ -0,0 +1,4 @@
+14
+42
+12
+4.500000

examples/closures/expected/0309-closures-literal-as-bare-fn-param.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0309-closures-literal-as-bare-fn-param.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0309-closures-literal-as-bare-fn-param.stdout

@@ -0,0 +1,3 @@
+block=10
+arrow=10
+twice=7

examples/closures/expected/0310-closures-closure-literal-in-defer.exit

@@ -0,0 +1 @@
+0

examples/closures/expected/0310-closures-closure-literal-in-defer.stderr

@@ -0,0 +1 @@
+

examples/closures/expected/0310-closures-closure-literal-in-defer.stdout

@@ -0,0 +1,2 @@
+body
+defer closure: 42