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).

com/kdesc.cpp

@@ -2,6 +2,7 @@
 #include "command.h"
 #include "error.h"
 #include "file.h"
+#include "font_store.h"
 #include "ktype.h"
 #include "log.h"
 #include "argtype_set.h"
@@ -9,6 +10,52 @@
 #include "show.h"
 #include "util.h"
 
+static void font_usage()
+{
+    std::cout <<
+        "Font maintenance commands:\n"
+        "  --font                        List the available fonts\n"
+        "  --font list                   The same\n"
+        "  --font samples <output-dir>   Write a sample page of the available fonts\n"
+        "                                to <output-dir>/index.html\n"
+        "  --font samples <input-dir> <output-dir>\n"
+        "                                Write a sample page for the (not yet\n"
+        "                                installed) font files under <input-dir>\n"
+        "  --font install <input-dir>    Install the font files found under\n"
+        "                                <input-dir> into the user font directory\n"
+        "  --font install <input-dir> <output-dir>\n"
+        "                                Install into <output-dir> instead\n"
+        "  --font help                   This description\n"
+        "\n"
+        "Fonts are searched in the directories of the KLAMMERTEXT_FONTS\n"
+        "environment variable (colon-separated; default $HOME/.klammertext/fonts)\n"
+        "and then in the default font set.\n";
+}
+
+static void font_command(const strings_t& words)
+{
+    std::string verb = words.empty() ? "list" : words[0];
+    size_t n = words.size() - (words.empty() ? 0 : 1);
+    if (verb == "list" && n == 0) {
+        std::cout << boldblack << "Fonts\n" << black << describe_fonts();
+    } else if (verb == "samples" && n == 1) {
+        std::cout << "Font samples written to "
+                  << write_font_samples(words[1]) << "\n";
+    } else if (verb == "samples" && n == 2) {
+        std::cout << "Font samples written to "
+                  << write_font_samples(words[2], words[1]) << "\n";
+    } else if (verb == "install" && (n == 1 || n == 2)) {
+        std::cout << "Installing fonts from " << words[1] << ":\n"
+                  << install_fonts(words[1], n == 2 ? words[2] : "");
+    } else if (verb == "help") {
+        font_usage();
+    } else {
+        std::cout << "Unrecognized font command: --font " << join(words, " ")
+                  << "\n\n";
+        font_usage();
+    }
+}
+
 int main(int argc, char* argv[])
 {
     try {
@@ -22,6 +69,7 @@ int main(int argc, char* argv[])
         args.opt("input", "Input filename", "filename", "", "'text'");
         args.flag("targets", "Show targets defined by the input file");
         args.flag("klammers", "Show klammers defined by the input file");
+        args.var("font", "List installed fonts.  Enter \"--font help\" for font maintenance commands.");
         args.opt("v",  "'verbosity'", "n", "0", "'verbosity'");
 
         if (show_usage(argc, argv)) {
@@ -55,6 +103,19 @@ int main(int argc, char* argv[])
             describe_rewrite_patterns();
         }
 
+        // The --font subcommands operate on the Klammertext font store
+        // (infrastructure) and load no klammer set.
+        if (args.given("font")) {
+            strings_t words {};
+            for (const std::string& w : word_split(args.get("font"))) {
+                if (!w.empty()) {
+                    words.push_back(w);
+                }
+            }
+            font_command(words);
+            return 0;
+        }
+
         Machine M;
 
         strings_t input_filenames = args.as_vector("input");