refactor: improve JSR score (part 1)

[Natoandro]

• Add symbol documentations
• Fix slow types

Migration notes

...

• The change comes with new or modified tests
• Hard-to-understand functions have explanatory comments
• End-user documentation is updated to reflect the change

[linear]

MET-615 (sdk) improve JSR score

[codecov]

Codecov Report

Attention: Patch coverage is 24.00000% with 76 lines in your changes missing coverage. Please review.

Project coverage is 69.69%. Comparing base (25d5c24) to head (330d7d0).
Report is 4 commits behind head on main.

Files	Patch %	Lines
typegraph/deno/sdk/src/types.ts	14.28%	48 Missing ⚠️
typegraph/deno/sdk/src/typegraph.ts	10.00%	18 Missing ⚠️
typegraph/deno/sdk/src/runtimes/python.ts	0.00%	4 Missing ⚠️
typegraph/deno/sdk/src/envs/cli.ts	50.00%	2 Missing ⚠️
typegraph/deno/sdk/src/policy.ts	0.00%	2 Missing ⚠️
typegraph/deno/sdk/src/metagen.ts	85.71%	1 Missing ⚠️
typegraph/deno/sdk/src/utils/func_utils.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #807      +/-   ##
==========================================
- Coverage   69.92%   69.69%   -0.23%     
==========================================
  Files         139      142       +3     
  Lines       16181    16527     +346     
  Branches     1475     1477       +2     
==========================================
+ Hits        11314    11518     +204     
- Misses       4842     4984     +142     
  Partials       25       25              

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