Filenames with spaces; output beside the input file; warning fixes (from dev c08eb1bbfa4c)

- Filenames may contain spaces: quote on the command line; filename
  lists use a standalone "/" separator; unseparated names that do not
  exist are rejoined into names that do (announced); leading ~ expands.
- Without -o, output is written to the input file's directory; -o fully
  specifies the output directory and basename.
- "Word not parsed" warnings now appear without -v, only for text that
  survives removal, with correct line numbers.
- New tst/filename_test.sh regression suite.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

mac/katom.cpp

@@ -92,16 +92,39 @@ katom_list make_katoms_from_word(std::string s, const std::string& source_desc,
                 return klist;
             }
         }
-        if (verbose_level > 0) {
-        std::cerr << command_name
-                  << " [warning]: Word not parsed in "
-                  << source_desc << ", line " << line+1 << ":\n"
-                  << "      " << s << "\n"
-                  << "To include a special character (@, |, #, and ^), put \"^\" before it.\n";
-        //return std::vector{ std::make_shared<Katom>(s, Locator(), katom_t::word) };
-        //return std::vector{ std::make_shared<Katom>(s, katom_t::word, Locator(source_desc, line, chr)) };
+        Katom k(s, katom_t::word, Locator(source_desc, line, chr));
+        k.m_unparsed = true; // Warning deferred to warn_unparsed_katoms()
+        return std::vector{ k };
+    }
+}
+
+// Warn about words that matched no katom type -- but only those that
+// survive processing: text removed by #, ##, or #[...]#, replaced spans,
+// and literal content (definition interiors, @code bodies) never warn.
+// Called at the end of Machine::process_katoms(), after those passes have
+// marked the katoms.  Clears the flag after warning so repeated processing
+// of the same katom list does not warn twice.  With warn=false (the @eval
+// read-back sub-Machine, whose katoms hold machine-generated result text)
+// no warning is printed and every flag is cleared, so the katoms stay
+// silent after they are spliced into the calling Machine's list.
+void warn_unparsed_katoms(katom_list& katoms, bool warn)
+{
+    for (Katom& k : katoms) {
+        if (!k.m_unparsed) continue;
+        if (!warn) {
+            k.m_unparsed = false;
+            continue;
+        }
+        if (k.m_type != katom_t::ignored
+            && k.m_type != katom_t::replaced
+            && k.m_type != katom_t::literal) {
+            std::cerr << command_name
+                      << " [warning]: Word not parsed in "
+                      << k.m_loc.m_filename << ", line " << k.m_loc.m_line << ":\n"
+                      << "      " << k.m_text << "\n"
+                      << "To include a special character (@, |, #, and ^), put \"^\" before it.\n";
+            k.m_unparsed = false;
         }
-        return std::vector{ Katom(s, katom_t::word, Locator(source_desc, line, chr)) };
     }
 }