docs: expand .rules.md with model generation and commit type guidance

[vdusek]

Expands .rules.md with two improvements:

• Model generation: details the full regeneration flow — datamodel-code-generator config, the postprocess script, local poe commands, and how CI auto-triggers from apify/apify-docs PRs
• Commit types: clarifies which Conventional Commit types (feat/fix/perf/refactor/style) trigger a release and must be used for source code only, and maps the remaining types (test:, docs:, ci:, chore:, build:) to their correct scope

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.34%. Comparing base (6eb9aee) to head (df6c692).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #732      +/-   ##
==========================================
+ Coverage   95.30%   95.34%   +0.03%     
==========================================
  Files          45       45              
  Lines        5115     5115              
==========================================
+ Hits         4875     4877       +2     
+ Misses        240      238       -2     

Flag	Coverage Δ
integration	95.34% <ø> (+0.03%)	⬆️

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