feat(stdlib): add SameFileName to SysUtils

SameFileName compares two file names for equality. This is a partial,
Unix-only stub: an exact case-sensitive comparison, which is correct on
case-sensitive file systems. Case-insensitive platforms would need the
names folded before comparing, but the stdlib has no platform-variance
facility yet — system.pas hardcodes DirectorySeparator, PathSeparator
and LineEnding to their Unix values — so there is nothing to key the
case-folding on. When a FileNameCaseSensitive constant lands alongside
the other platform constants, the case-insensitive branch can be added.

e2e test asserts identical names match and differing names do not.

compiler/src/test/pascal/cp.test.e2e.sysutils.pas

@@ -45,6 +45,7 @@ type
     procedure TestRun_SetCurrentDir_ChangesDir;
     procedure TestRun_ExtractFileExt_ReturnsExt;
     procedure TestRun_BoolToStr_TrueAndFalse;
+    procedure TestRun_SameFileName_ExactMatch;
     procedure TestRun_PlatformConstants;
     procedure TestRun_GetCurrentDir_ReturnsNonEmpty;
     procedure TestRun_FileAge_ReturnsTimestamp;
@@ -534,6 +535,16 @@ const
         end.
         ''';
 
+  SrcSameFileName =
+    '''
+        program P;
+        uses SysUtils;
+        begin
+          WriteLn(SameFileName('a/b.pas', 'a/b.pas'));
+          WriteLn(SameFileName('a/b.pas', 'a/c.pas'))
+        end.
+        ''';
+
   SrcPlatformConstants =
     '''
         program P;
@@ -659,6 +670,25 @@ begin
   end;
 end;
 
+procedure TE2ESysUtilsTests.TestRun_SameFileName_ExactMatch;
+var
+  Output: string;
+  RCode: Integer;
+  Lines: TStringList;
+begin
+  if not ToolchainAvailable() then begin Ignore('toolchain unavailable'); Exit; end;
+  AssertTrue('compile+run', CompileAndRunWithRTL(SrcSameFileName, Output, RCode));
+  AssertEquals('exit code 0', 0, RCode);
+  Lines := TStringList.Create();
+  try
+    Lines.Text := Trim(Output);
+    AssertEquals('identical names match',   'True',  Lines.Strings[0]);
+    AssertEquals('different names differ',  'False', Lines.Strings[1]);
+  finally
+    Lines.Free();
+  end;
+end;
+
 procedure TE2ESysUtilsTests.TestRun_PlatformConstants;
 var
   Output: string;

stdlib/src/main/pascal/sysutils.pas

@@ -64,6 +64,18 @@ function BoolToStr(B: Boolean; AUseBoolStrs: Boolean = False): string;
   on paths that do not traverse symlinks. }
 function ExpandFileName(const APath: string): string;
 
+{ SameFileName — compare two file names for equality.
+
+  PARTIAL STUB: an exact, case-sensitive string comparison.  This is correct
+  only on case-sensitive file systems (Unix); case-insensitive platforms
+  (Windows) would need the names folded before comparing.  Blaise has no
+  platform-variance facility yet — system.pas hardcodes DirectorySeparator,
+  PathSeparator and LineEnding to their Unix values — so there is nothing to
+  key the case-folding on.  When a FileNameCaseSensitive constant lands
+  alongside the other platform constants, add the case-insensitive branch
+  here under that guard. }
+function SameFileName(const S1, S2: string): Boolean;
+
 implementation
 
 constructor Exception.Create(AMessage: string);
@@ -145,4 +157,12 @@ begin
     Result := '/';
 end;
 
+{ PARTIAL STUB — exact compare only; see the interface note.  Correct on
+  case-sensitive (Unix) file systems; needs a case-insensitive branch for
+  Windows. }
+function SameFileName(const S1, S2: string): Boolean;
+begin
+  Result := S1 = S2;
+end;
+
 end.