go: lex.sx — raw string literals (backtick) + 9 tests [nothing]

Adds Go raw string literals per Go spec § String literals:
backtick-delimited, no escape processing, may span multiple
lines, '\r' chars discarded from the value.

gl-read-raw-string! mirrors gl-read-string! but skips escape
handling and the \r filter. scan! routes the leading backtick
to it; emits "string" type (same as interpreted strings — no
need to distinguish at parse/type time).

lex 123/123.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/go/tests/lex.sx

@@ -143,7 +143,38 @@
 (go-test "imag: ASI at newline" (tok-types "1i\n") (list "imag" "semi" "eof"))
 
 ;; ── string literals ───────────────────────────────────────────────
+(go-test "raw: simple" (tok-values "`hello`") (list "hello" "\n" nil))
+(go-test "raw: empty" (tok-values "``") (list "" "\n" nil))
+(go-test
+  "raw: backslash literal — no escape processing"
+  (tok-values "`a\\nb`")
+  (list "a\\nb" "\n" nil))
+(go-test
+  "raw: multi-line"
+  (tok-values "`line1\nline2`")
+  (list "line1\nline2" "\n" nil))
+(go-test
+  "raw: contains double-quote"
+  (tok-values "`say \"hi\"`")
+  (list "say \"hi\"" "\n" nil))
+(go-test
+  "raw: CR stripped (Go spec § String literals)"
+  (tok-values "`a\r\nb`")
+  (list "a\nb" "\n" nil))
+(go-test "raw: type" (tok-types "`x`") (list "string" "semi" "eof"))
+
+;; ── rune literals ─────────────────────────────────────────────────
+(go-test
+  "raw: then +"
+  (tok-types "`x` + 1")
+  (list "string" "op" "int" "semi" "eof"))
+(go-test
+  "raw: ASI at newline after"
+  (tok-types "`abc`\n")
+  (list "string" "semi" "eof"))
 (go-test "string: empty" (tok-values "\"\"") (list "" "\n" nil))
+
+;; ── comments ──────────────────────────────────────────────────────
 (go-test "string: hello" (tok-values "\"hello\"") (list "hello" "\n" nil))
 (go-test
   "string: with space"
@@ -155,14 +186,12 @@
   "string: escape backslash"
   (tok-values "\"a\\\\b\"")
   (list "a\\b" "\n" nil))
-(go-test "string: type" (tok-types "\"x\"") (list "string" "semi" "eof"))
 
-;; ── rune literals ─────────────────────────────────────────────────
+;; ── operators & punctuation ───────────────────────────────────────
+(go-test "string: type" (tok-types "\"x\"") (list "string" "semi" "eof"))
 (go-test "rune: simple" (tok-values "'a'") (list "a" "\n" nil))
 (go-test "rune: escape" (tok-values "'\\n'") (list "\n" "\n" nil))
 (go-test "rune: type" (tok-types "'a'") (list "rune" "semi" "eof"))
-
-;; ── comments ──────────────────────────────────────────────────────
 (go-test "line comment" (tok-types "// ignored") (list "eof"))
 (go-test "line comment then code" (tok-values "// hi\nx") (list "x" "\n" nil))
 (go-test "block comment" (tok-types "/* a b c */") (list "eof"))
@@ -175,7 +204,7 @@
   (tok-types "x /* multi\nline */ y")
   (list "ident" "semi" "ident" "semi" "eof"))
 
-;; ── operators & punctuation ───────────────────────────────────────
+;; ── automatic semicolon insertion (Go spec § Semicolons) ──────────
 (go-test
   "ops: arithmetic"
   (tok-values "+ - * / %")
@@ -200,8 +229,6 @@
   "punct: comma colon dot"
   (tok-values ", : .")
   (list "," ":" "." nil))
-
-;; ── automatic semicolon insertion (Go spec § Semicolons) ──────────
 (go-test
   "ASI: after ident at newline"
   (tok-types "x\ny")
@@ -213,6 +240,8 @@
   (tok-types "\"hi\"\n")
   (list "string" "semi" "eof"))
 (go-test "ASI: after rune" (tok-types "'a'\n") (list "rune" "semi" "eof"))
+
+;; ── short program ─────────────────────────────────────────────────
 (go-test
   "ASI: after )"
   (tok-types "f()\n")
@@ -222,37 +251,45 @@
   (tok-types "x[0]\n")
   (list "ident" "op" "int" "op" "semi" "eof"))
 (go-test "ASI: after }" (tok-types "{}\n") (list "op" "op" "semi" "eof"))
+
+;; ── report ────────────────────────────────────────────────────────
 (go-test "ASI: after ++" (tok-types "i++\n") (list "ident" "op" "semi" "eof"))
+
 (go-test
   "ASI: NOT after +"
   (tok-types "x +\ny")
   (list "ident" "op" "ident" "semi" "eof"))
+
 (go-test
   "ASI: NOT after ("
   (tok-types "f(\nx)")
   (list "ident" "op" "ident" "op" "semi" "eof"))
+
 (go-test
   "ASI: blank lines collapse — single semi only"
   (tok-types "x\n\n\ny")
   (list "ident" "semi" "ident" "semi" "eof"))
+
 (go-test
   "ASI: at EOF after ident"
   (tok-types "x")
   (list "ident" "semi" "eof"))
+
 (go-test
   "ASI: explicit semi"
   (tok-types "x;y")
   (list "ident" "semi" "ident" "semi" "eof"))
 
-;; ── short program ─────────────────────────────────────────────────
 (go-test
   "short-decl: x := 42 (types)"
   (tok-types "x := 42")
   (list "ident" "op" "int" "semi" "eof"))
+
 (go-test
   "short-decl: x := 42 (values)"
   (tok-values "x := 42")
   (list "x" ":=" "42" "\n" nil))
+
 (go-test
   "func decl shape"
   (tok-types "func foo() int { return 0 }")
@@ -269,5 +306,4 @@
     "semi"
     "eof"))
 
-;; ── report ────────────────────────────────────────────────────────
 (define go-lex-test-summary (str "lex " go-test-pass "/" go-test-count))