implement contract address configuration integrity checks in reporting

[Abolax123]

Closes #309

Summary

• Enforce integrity checks for the reporting dependency contract address configuration (reject self-reference and any duplicated slot).
• Add public verify_dependency_address_set helper to preflight configurations without auth/storage writes.
• Migrate reporting errors to #[contracterror] so try_* client calls decode contract errors correctly.

Security notes

• Validation is constant time and purely structural (5 fixed slots).
• Prevents ambiguous routing / accidental self-loops (any dependency address equal to Env::current_contract_address() is rejected).
• Prevents silent role aliasing where two logical dependencies point at the same contract ID (duplicates rejected).
• Soroban/Stellar contract IDs do not have an EVM-style “zero address”; malformed inputs at this layer are primarily structural issues (duplicates/self-reference). Correctness of which deployments are referenced remains an off-chain governance/deployment concern.

Test plan

• cargo test -p reporting --all-features