feat: split up model building, extract contexts

[erdos]

No description provided.

[codecov]

Codecov Report

Merging #147 (6e0b879) into master (4e29ca3) will increase coverage by 0.03%.
The diff coverage is 98.21%.

@@            Coverage Diff             @@
##           master     #147      +/-   ##
==========================================
+ Coverage   93.11%   93.14%   +0.03%     
==========================================
  Files          27       27              
  Lines        1887     1896       +9     
  Branches      105      105              
==========================================
+ Hits         1757     1766       +9     
  Misses         25       25              
  Partials      105      105              

Impacted Files	Coverage Δ
src/stencil/spec.clj	100.00% <ø> (ø)
src/stencil/model.clj	96.62% <97.61%> (-0.09%)	⬇️
src/stencil/model/numbering.clj	94.73% <100.00%> (+0.29%)	⬆️
src/stencil/model/style.clj	98.46% <100.00%> (+0.10%)	⬆️
src/stencil/postprocess/fragments.clj	93.75% <100.00%> (+0.35%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more