refactor: Remove unused contract address fields from chain config

[Zalens]

Summary

• Removes 9 unused contract address fields (safeSingletonAddress, safeProxyFactoryAddress, multiSendAddress, multiSendCallOnlyAddress, fallbackHandlerAddress, signMessageLibAddress, createCallAddress, simulateTxAccessorAddress, safeWebAuthnSignerFactoryAddress) from the Chain model and API response
• These fields were added in July 2024 but never populated — they appear empty on both staging and production
• Removes the ContractAddressesSerializer, model fields, test factory assignments, and test expectations
• Includes a migration to drop the columns from the database

Closes PLA-1142

Test plan

• All 235 existing tests pass
• Verify staging API response no longer includes contractAddresses
• Confirm no downstream clients depend on these fields

🤖 Generated with Claude Code

[coveralls]

Pull Request Test Coverage Report for Build 23534977119

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.006%) to 99.576%

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Totals
Change from base Build 23254455469:	-0.006%
Covered Lines:	1410
Relevant Lines:	1416

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💛 - Coveralls

[compojoom]

@Zalens do we also need a PR on the client-gateway? The chain object there has those fields as well.

[Zalens]

@Zalens do we also need a PR on the client-gateway? The chain object there has those fields as well.

Good point, I'll check

[Zalens]

@compojoom PR is here: safe-global/safe-client-gateway#2990

[PooyaRaki]

@claude review

[claude]

Claude finished @PooyaRaki's task —— View job

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Review

• Read changed files
• Check for stale references to removed fields
• Analyze code quality, bugs, security, performance, test coverage

Looks good. Clean removal across model, serializer, factory, and tests. The migration is correct and the dependency chain is proper (0054 → 0055).

One minor note:

• No admin.py cleanup needed — confirmed no references to these fields exist in admin configuration.
• No stale references — grep across src/ confirms only the old migration files (0043, 0044, 0046, 0047) still reference these field names, which is expected and correct (migration history must be preserved).
• Test coverage is adequate — the test_json_payload_format tests for both list and detail views confirm contractAddresses is no longer in the response.

No issues found. Approve.

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