STR-1344: rpc state cache does not get updated

[storopoli]

Description

Turns out that the RPC server was trying to deserialize the MachineState as ContractState. That would never had worked.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature/Enhancement (non-breaking change which adds functionality or enhances an existing one)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactor
• New or updated tests
• Dependency Update

Notes to Reviewers

The duty tracker serializes all the contracts:

bridge-1-1          | 2025-05-14T19:13:20.780672Z DEBUG duty_tracker::contract_persister: committing all active contracts num_contracts=1
bridge-1-1          | 2025-05-14T19:13:40.848958Z  INFO alpen_bridge::rpc_server: initializing the RPC server initial contract cache fill before_num_contracts=1
bridge-1-1          | 2025-05-14T19:13:40.863640Z DEBUG alpen_bridge::rpc_server: Contracts cache refreshed after_num_contracts=1

Checklist

• I have performed a self-review of my code.
• I have commented my code where necessary.
• I have updated the documentation if needed.
• My changes do not introduce new warnings.
• I have added (where necessary) tests that prove my changes are effective or that my feature works.
• New and existing tests pass with my changes.

Related Issues

STR-1344

[codecov]

Codecov Report

Attention: Patch coverage is 4.21053% with 91 lines in your changes missing coverage. Please review.

Project coverage is 51.66%. Comparing base (9d7d79f) to head (b6a45a4).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
bin/alpen-bridge/src/rpc_server.rs	0.00%	82 Missing ⚠️
bin/alpen-bridge/src/mode/operator.rs	0.00%	6 Missing ⚠️
crates/duty-tracker/src/contract_persister.rs	0.00%	3 Missing ⚠️

@@            Coverage Diff             @@
##             main     #142      +/-   ##
==========================================
- Coverage   51.86%   51.66%   -0.21%     
==========================================
  Files         147      147              
  Lines       24675    24783     +108     
==========================================
+ Hits        12798    12803       +5     
- Misses      11877    11980     +103     

Files with missing lines	Coverage Δ
bin/alpen-bridge/src/config.rs	95.23% <100.00%> (+0.23%)	⬆️
crates/duty-tracker/src/contract_persister.rs	0.00% <0.00%> (ø)
bin/alpen-bridge/src/mode/operator.rs	0.00% <0.00%> (ø)
bin/alpen-bridge/src/rpc_server.rs	0.00% <0.00%> (ø)

... and 5 files with indirect coverage changes

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[ProofOfKeags]

don't leave redundant comments lol

[storopoli]

redundant!? You don't know how many times I've got burned by a lock? At Alpen I think I've seen at least 2 times. I'm gonna die in this hill, this is not redundant. I'll remove the comment once we have STM-ish lock-free data structures in the Bridge 😄

[ProofOfKeags]

no what I mean is that the comment provides no additional value over just dropping the lock