migration routers

[cody-littley]

Describe your changes and provide context

Use the migration router primitives to construct the migration workflows we will need.

Use the following link to view the README in rendered form. Suggested read prior to reviewing code. https://github.com/sei-protocol/sei-chain/blob/cjl/migration-integration/sei-db/state_db/sc/migration/README.md

Testing performed to validate your change

unit tests

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	May 6, 2026, 3:51 PM

[codecov]

Codecov Report

❌ Patch coverage is 66.26506% with 84 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.09%. Comparing base (68b9eeb) to head (4265c58).

Files with missing lines	Patch %	Lines
sei-db/state_db/sc/migration/router_builder.go	55.69%	36 Missing and 34 partials ⚠️
sei-db/state_db/sc/migration/write_mode.go	0.00%	11 Missing ⚠️
sei-db/state_db/sc/migration/router_kvstore.go	95.23%	2 Missing ⚠️
sei-db/state_db/sc/migration/migration_manager.go	94.11%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3336      +/-   ##
==========================================
+ Coverage   59.03%   59.09%   +0.05%     
==========================================
  Files        2102     2105       +3     
  Lines      173237   173417     +180     
==========================================
+ Hits       102277   102485     +208     
+ Misses      62083    62015      -68     
- Partials     8877     8917      +40     

Flag	Coverage Δ
sei-chain-pr	76.04% <66.26%> (?)
sei-db	70.41% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
sei-db/state_db/sc/migration/migration_types.go	80.00% <ø> (ø)
sei-db/state_db/sc/migration/module_router.go	100.00% <100.00%> (ø)
sei-db/state_db/sc/migration/store_keys.go	100.00% <100.00%> (ø)
sei-db/state_db/sc/migration/thread_safe_router.go	100.00% <100.00%> (ø)
sei-db/state_db/sc/migration/migration_manager.go	95.48% <94.11%> (-0.77%)	⬇️
sei-db/state_db/sc/migration/router_kvstore.go	95.23% <95.23%> (ø)
sei-db/state_db/sc/migration/write_mode.go	0.00% <0.00%> (ø)
sei-db/state_db/sc/migration/router_builder.go	58.45% <55.69%> (+58.45%)	⬆️

... and 1 file with indirect coverage changes

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