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).

doc/install/linux_source_install.md

@@ -51,7 +51,7 @@ Klammertext's runtime environment is provided by a single self-configuring
 file. Source it from your shell profile (e.g., `~/.bashrc` or `~/.zshrc`):
 
 ```bash
-source /path/to/klammertext/mac/env/runtime.env
+source /path/to/klammertext/env/runtime.env
 ```
 
 It self-locates `KLAMMERTEXT_HOME` from its own path, adds `bin/` and
@@ -59,7 +59,7 @@ It self-locates `KLAMMERTEXT_HOME` from its own path, adds `bin/` and
 TeX Live is installed there), sets `LD_LIBRARY_PATH` so `libklammertext.so` is
 found, and sets the LSan suppressions. There is no per-host or per-OS variable
 to set. For a TeX Live or library in a non-standard location, add it to an
-optional, gitignored `mac/env/runtime.env.local` (sourced at the end).
+optional, gitignored `env/runtime.env.local` (sourced at the end).
 
 After editing your shell profile, reload it:
 
@@ -70,7 +70,7 @@ source ~/.bashrc
 
 ## Configure the build
 
-No build configuration is needed. The single `mac/env/makefile.env` is
+No build configuration is needed. The single `env/makefile.env` is
 cross-platform: it reads `KLAMMERTEXT_HOME` from the environment (set by
 `runtime.env` above), auto-detects the platform with `uname`, and auto-detects
 Python with `python3-config` — no hardcoded version and no per-host file to
@@ -149,7 +149,7 @@ from the gitignored escape hatch instead, and install the SKS's extra packages
 into it yourself (the package list is in `doc/install/texlive_additional_packages.sh`):
 
 ```bash
-cat >> "$KLAMMERTEXT_HOME/mac/env/runtime.env.local" <<'EOF'
+cat >> "$KLAMMERTEXT_HOME/env/runtime.env.local" <<'EOF'
 export KLAMMERTEXT_TEXLIVE_BIN=/path/to/texlive/bin/x86_64-linux
 export PATH="$KLAMMERTEXT_TEXLIVE_BIN:$PATH"
 EOF