fix: Use 2 letter code for hooks API language header

[finnian0826]

Description

hooks repo .crowdin.yml (here) uses 2 letter code for language, update API header to use that. Same as dapp-list.

Test plan

Unit tests updated

Related issues

• Related to ACT-1331

Backwards compatibility

Yes

Network scalability

If a new NetworkId and/or Network are added in the future, the changes in this PR will:

• Continue to work without code changes, OR trigger a compilation error (guaranteeing we find it when a new network is added)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.31%. Comparing base (30e9d0f) to head (47ebb1f).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5846      +/-   ##
==========================================
+ Coverage   87.30%   87.31%   +0.01%     
==========================================
  Files         731      731              
  Lines       31266    31267       +1     
  Branches     5546     5543       -3     
==========================================
+ Hits        27296    27300       +4     
+ Misses       3746     3743       -3     
  Partials      224      224              

Files	Coverage Δ
src/positions/saga.ts	90.81% <100.00%> (+0.04%)	⬆️

... and 1 file with indirect coverage changes

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