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/image/image.k

@@ -16,6 +16,13 @@
 # @@@argtype pixels | a pixel count :pattern \d+px @@@
 # @@image.k basename : Image read from a file @@
 # @@image.html basename | width | height : @eval import image ; result = image.image(K) eval@ @@
+
+@@@argtype image_hpos |
+  horizontal position of an image
+  :pattern left^|center^|right^|none
+  :default center
+@@@
+
 @@image
   basename
   :id
@@ -23,7 +30,7 @@
   @caption_arguments@
   :vmargin.bool true
   :center.bool true
-  :hpos.hpos center
+  :hpos.image_hpos
   :rel
   :abswidth.number 0.0
   :border.bool false
@@ -32,13 +39,13 @@
 @@
 
 @@image_grid
-  image_specs.rest
+  image_specs.rest(2)
   :caption
   :number.bool true
   :cell_number.bool false
   :landscape.bool false
   :scale.number 0.98
-  :caption_side.side bottom
+  :caption_side.caption_side
   :caption_side_center.bool true
 #
   :thumbnail.bool false