fix: change map key parsing precedence from PRIMARY to UNARY

In wren_compiler.c, the map() function now parses map keys with PREC_UNARY
instead of PREC_PRIMARY, allowing unary operators like negation and bitwise
NOT in key expressions. Added test/language/map/bad_key_precedence.wren to
verify that binary operators (e.g., 1 + 2) still produce an error when used
as keys, and test/language/map/precedence.wren to validate correct parsing
of primary, call, and unary expressions in map keys.

src/vm/wren_compiler.c

@@ -1987,7 +1987,7 @@ static void map(Compiler* compiler, bool allowAssignment)
     if (peek(compiler) == TOKEN_RIGHT_BRACE) break;
 
     // The key.
-    parsePrecedence(compiler, false, PREC_PRIMARY);
+    parsePrecedence(compiler, false, PREC_UNARY);
     consume(compiler, TOKEN_COLON, "Expect ':' after map key.");
     ignoreNewlines(compiler);