Fix: refactor postman with viem

[VGau]

This PR implements issue(s) #

Checklist

• I wrote new tests for my new core changes.
• I have successfully ran tests, style checker and build against my new changes locally.
• If this change is deployed to any environment (including Devnet), E2E test coverage exists or is included in this
  PR.
• I have informed the team of any breaking changes if there are any.

---

Note

High Risk
Large refactor of the Postman service wiring/entrypoint, configuration parsing, and blockchain interaction stack (moving from linea-sdk/ethers to Viem) which can affect message claiming/anchoring behavior and production runtime. Docker/CI changes also alter how the service is built and started, increasing integration risk.

Overview
Refactors the Postman service to a new Viem-based application structure: introduces PostmanApp plus L1ToL2App/L2ToL1App and a DI-style PostmanContainer, and removes the legacy PostmanServiceClient/scripts/runPostman.ts startup path.

Switches Postman dependencies from @consensys/linea-sdk/ethers (and better-sqlite3) to @consensys/linea-sdk-core, @consensys/linea-sdk-viem, viem, and zod, and updates config handling to Zod-validated schemas with a new envLoader (including web3signer/TLS signer support and additional claiming retry controls like MAX_BUMPS_PER_CYCLE/MAX_RETRY_CYCLES).

Updates runtime and tooling: Docker image now builds sdk-core/sdk-viem and runs dist/src/main.js, GitHub workflow builds @consensys/linea-postman^... and runs sdk-viem tests, docker-compose postman depends on l2-node-besu, and Postman CLI scripts are rewritten to use Viem clients/ABI encoding. Adds/updates Jest coverage ignores and introduces new unit tests for the new app/config wiring.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.88%. Comparing base (f23c478) to head (b07f30b).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##              main    #2617       +/-   ##
============================================
+ Coverage     9.70%   58.88%   +49.18%     
- Complexity       0     1620     +1620     
============================================
  Files          454      453        -1     
  Lines        18530    18528        -2     
  Branches      2014     2014               
============================================
+ Hits          1799    10911     +9112     
+ Misses       16731     6948     -9783     
- Partials         0      669      +669     

Flag	Coverage Δ		*Carryforward flag
hardhat	96.63% <ø> (+0.10%)	⬆️	Carriedforward from 111ab53
kotlin	54.71% <ø> (+54.61%)	⬆️

*This pull request uses carry forward flags. Click here to find out more.
see 294 files with indirect coverage changes

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