feat: Edge V2 migration opt-in, capacity budget for migration

[khvn26]

• Add EDGE_V2_MIGRATION_READ_CAPACITY_BUDGET setting
• Add per-project read capacity budget
• Enable incomplete Edge V2 migrations when capacity budget exceeded

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.17%. Comparing base (e8d1337) to head (031a0df).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3881      +/-   ##
==========================================
+ Coverage   96.01%   96.17%   +0.16%     
==========================================
  Files        1138     1141       +3     
  Lines       36443    36457      +14     
==========================================
+ Hits        34992    35064      +72     
+ Misses       1451     1393      -58     

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