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.h

@@ -3,6 +3,7 @@
 // Delusions of generality, but it's really just for Klammertext commands.
 
 #include <map>
+#include <set>
 #include <ranges>
 #include <algorithm>
 #include <regex>
@@ -52,12 +53,23 @@ public:
     void flag(const std::string& name, const std::string& desc);
     void req(const std::string& name, const std::string& desc, const std::string& regex_pattern="'text'");
     void opt(const std::string& name, const std::string& desc="", const std::string& parameter="", const std::string& default_value="", const std::string& regex_pattern="text");
+    // A variadic option: --name collects every following word up to the
+    // next -/-- token (zero or more).  get(name) returns the words
+    // space-joined; given(name) distinguishes "--name with no words"
+    // from an absent --name.  Used for subcommand-style interfaces
+    // (kdesc --font install <dir>).
+    void var(const std::string& name, const std::string& desc);
 
     void update_width(Arg arg);
 
     void check_flags_and_options(std::string command, std::vector<std::string>& words);
     void parse_flags(std::vector<std::string>& words, std::map<std::string, std::string>& named_args);
     void parse_optional(std::vector<std::string>& words, std::map<std::string, std::string>& named_args);
+    void parse_vars(std::vector<std::string>& words, std::map<std::string, std::string>& named_args);
+
+    // True when the named variadic option appeared on the command line
+    // (even with no following words).
+    bool given(const std::string& name) { return m_given.contains(name); };
 
     void parse_positional(
         std::string command, // std::vector<std::string> words,
@@ -98,6 +110,8 @@ public:
     std::vector<std::string> m_req_names {};
     std::vector<std::string> m_flag_names {};
     std::vector<std::string> m_opt_names {};
+    std::vector<std::string> m_var_names {};
+    std::set<std::string> m_given {};
     std::vector<std::string> m_hyphen_markers {};
     long unsigned int m_syntax_size = 0;
 };