feat(stream): expose current operator in StreamInfo and on-chain getter (#396)

[DonaldXoftDev]

What

Adds pub operator: Option

to StreamInfo and synchronizes the operator address on delegation, revocation, and stream state reads.

Why

Closes #396

Stream recipients previously had no way to inspect on-chain which delegated operator (if any) could cancel, pause, or modify their stream without indexing past operator_set and operator_revoked events from genesis.

How

• contracts/stream/src/storage.rs: Added pub operator: Option to StreamInfo struct and cleaned up syntax annotations.
• contracts/stream/src/lib.rs: Initialized StreamInfo.operator to None in initialize(), updated set_operator() and
  evoke_operator() to persist operator state to StreamInfo, and verified operator(env: Env) -> Option public getter.
• contracts/stream/src/state.rs: Updated legacy fallback state loading to populate operator from DataKey::Operator.
• contracts/stream/src/tests.rs: Added unit tests verifying StreamInfo.operator matches operator() across initialization, delegation, revocation, and stream lifecycle mutations.
• contracts/governor/src/storage.rs & contracts/oracle/src/lib.rs: Added missing Clone derives on DataKey for shared RBAC storage traits.

Testing

• cargo fmt --all --check (Passed)
• cargo clippy --workspace --exclude conduit-integration-tests --target wasm32-unknown-unknown -- -D warnings (Passed)
• cargo build -p drip-stream --target wasm32-unknown-unknown --release (Passed)
• cargo build -p drip-factory --target wasm32-unknown-unknown --release (Passed)
• cargo build -p drip-governor --target wasm32-unknown-unknown --release (Passed)

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