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).

sks/document/document.k

@@ -1,8 +1,10 @@
 @@@argtype document_structure |
   Structure of a document: plain, article, or book
   :pattern plain^|article^|book
+  :default plain
 @@@
 
+
 @@document.k
 :title
 :subtitle
@@ -19,7 +21,7 @@
 :toc.bool false
 ]#
 
-:structure.document_structure plain
+:structure.document_structure
 
 :text
 :files
@@ -38,9 +40,6 @@
 :include_sks_js.bool true
 :include_fonts.bool true
 
-:local_fonts.list linux-libertine
-:google_fonts.list Inconsolata Open+Sans:wght^@500 Libre+Baskerville
-
 :serif_font Crimson Pro
 :sans_font Open Sans
 :mono_font Inconsolata