fix: add caller authentication and storage pinning to asserter-consumer (#157)

[bilhokista]

Summary

Closes #157.

contracts/asserter-consumer/src/lib.rs allowed any caller to invoke create_assertion_as_self with arbitrary tholos_id, token_id, and outcome. Because the assertion is posted using the contract's own address as the asserter, an unauthenticated caller could front-run or hijack the contract's bond capital, impersonating the contract without authorization. Additionally, tholos_id and token_id were passed per call rather than pinned.

Key Changes

• Added initialize(env, admin, tholos_id, token_id) with admin.require_auth() and single-initialization guard via DataKey::Admin.
• Stored admin, tholos_id, and token_id in instance storage via DataKey enum.
• Added Error::AlreadyInitialized = 5 and Error::NotInitialized = 6 to contracts/tholos-client/src/lib.rs.
• Required admin.require_auth() in create_assertion_as_self and retrieved tholos_id and token_id from instance storage.
• Updated get_status to query using pinned tholos_id from instance storage instead of accepting an unverified parameter.
• Added regression tests in contracts/asserter-consumer/src/test.rs covering uninitialized rejection, unauthorized caller rejection, double initialization rejection, and valid authenticated flow.

Test plan

• cargo fmt --check, cargo clippy --workspace --all-targets -- -D warnings, and cargo test pass locally
  • cargo test -p asserter-consumer: 10 passed, 0 failed
  • cargo test -p demo-consumer: 6 passed, 0 failed
  • cargo clippy -p asserter-consumer -p tholos-client --all-targets -- -D warnings: clean (0 warnings)
  • cargo fmt --check: clean
• CONTRACT.md updated if the public interface changed
• scripts/testnet-smoke.sh run against testnet
• What you manually verified: verified unauthorized caller revert, double init revert, and successful assertion flow under pinned storage.

[collinsezedike]

@bilhokista Closing this, issue #157 is assigned to another contributor who asked for it first. Feel free to pick up another open issue.