feat: PostScript stream processing with account code injection

filter/kyofilter

@@ -24,5 +24,24 @@ def get_account_code(options):
     return code.zfill(8)
 
 
+def process_stream(lines, account_code):
+    if not account_code:
+        yield from lines
+        return
+
+    inject = f"({account_code}) statusdict /setmanagementnumber get exec\n".encode()
+    injected = False
+
+    for line in lines:
+        stripped = line.rstrip(b'\r\n')
+        if not injected and (stripped == b'%%EndSetup' or stripped.startswith(b'%%Page:')):
+            yield inject
+            injected = True
+        yield line
+
+    if not injected:
+        sys.stderr.write("kyofilter: WARNING: no injection point found in PostScript stream\n")
+
+
 if __name__ == '__main__':
     pass