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).

fnt/libre-baskerville.css

@@ -0,0 +1,13 @@
+/* libre-baskerville-regular - latin */
+@font-face {
+  font-family: 'Libre Baskerville';
+  font-style: normal;
+  font-weight: 400;
+  src: url('libre-baskerville/libre-baskerville-v5-latin-regular.eot'); /* IE9 Compat Modes */
+  src: local('Libre Baskerville'), local('LibreBaskerville-Regular'),
+       url('libre-baskerville/libre-baskerville-v5-latin-regular.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
+       url('libre-baskerville/libre-baskerville-v5-latin-regular.woff2') format('woff2'), /* Super Modern Browsers */
+       url('libre-baskerville/libre-baskerville-v5-latin-regular.woff') format('woff'), /* Modern Browsers */
+       url('libre-baskerville/libre-baskerville-v5-latin-regular.ttf') format('truetype'), /* Safari, Android, iOS */
+       url('libre-baskerville/libre-baskerville-v5-latin-regular.svg#LibreBaskerville') format('svg'); /* Legacy iOS */
+}