Typed arguments, calculated tables, spans, closed-world fonts, top-level fnt/ and env/

Sync with klammertext-dev through b90b0e09:

- Argument types end to end: :python_cast values are applied (Python
  @eval receives real bools/numbers/lists), argument values are
  validated against their argtype patterns with the argtype's
  description as the error message, argtypes can declare :default
  (overridable per declaration), and parameterized type families are
  supported: rest(N) casts a rest argument to an N-dimensional list
  (bar-count = dimension).
- Unified indexed_range syntax (selector with parenthesized subsets,
  composable mnemonic names) for table lines and spans.
- Table klammer: caption fonts fixed in both targets, :column_width /
  :leading / :colsep wired, :colspan and :rowspan render (HTML
  attributes; \multicolumn / \multirow), calculated cell values (:calc)
  with prefix operators, display-precision semantics, :calc_format and
  :decimal period|comma.
- Fonts: closed-world resolution on the Klammertext font store
  (infrastructure in mac/font_store; no Google Fonts links or fetch).
  Default fonts live in the top-level fnt/; additional fonts install
  into KLAMMERTEXT_FONTS directories via kdesc --font (list, samples,
  preview, install — classification by font metadata).  CSS font family
  names are quoted (digit-initial families were silently lost).
- Environment files moved from mac/env/ to the top-level env/; shell
  profiles source env/runtime.env.  Dead per-host variants removed.
- Container: fnt/ ships in the image; curl removed (no network use).

mac/argv.cpp

@@ -145,6 +145,40 @@ void Argv::opt(const std::string& name, const std::string& desc, const std::stri
     update_width(arg);
 }
 
+void Argv::var(const std::string& name, const std::string& desc)
+{
+    (void)K::log(2, name, desc);
+    Arg arg {};
+    arg.m_type = "var";
+    arg.m_name = name;
+    arg.m_desc = get_regex_desc(desc);
+    arg.m_syntax = arg.symbol();
+    m_args[name] = arg;
+    m_names.push_back(name);
+    m_var_names.push_back(name);
+    m_hyphen_markers.push_back(flag_name(name));
+    update_width(arg);
+}
+
+void Argv::parse_vars(strings_t& words, string_map& named_args)
+{
+    for (const std::string& name : m_var_names) {
+        auto it = std::ranges::find(words, flag_name(name));
+        named_args[name] = "";
+        if (it == words.end()) {
+            continue;
+        }
+        m_given.insert(name);
+        auto first = it + 1;
+        auto last = first;
+        while (last != words.end() && !(*last).empty() && (*last)[0] != '-') {
+            last++;
+        }
+        named_args[name] = join(strings_t(first, last), " ");
+        words.erase(it, last);
+    }
+}
+
 void Argv::usage_line(Arg arg)
 {
     std::cout.fill(' ');
@@ -330,6 +364,7 @@ Argv::classify_arguments(int argc, char* argv[], bool full_parse)
     if (full_parse) {
         check_flags_and_options(argv[0], words);
     }
+    parse_vars(words, named_args);
     parse_flags(words, named_args);
     parse_optional(words, named_args);
     parse_positional(argv_to_string(argc, argv), join(words, " "), named_args);