fix(reborn): harden runtime network policy handoff

[serrrfirat]

Summary

• remove the stale network_policy field from WasmRuntimeCredentialRequest so credential providers cannot drift from the staged runtime policy handoff
• add WASM/script/MCP adapter composition coverage through real HostHttpEgressService + NetworkObligationPolicyStore
• restore staged policy consumption before request validation so one-shot policy handoffs cannot be reused after pre-transport request failures

Verification

• cargo fmt --check
• cargo test -p ironclaw_wasm --test wasm_http_adapter_contract
• cargo test -p ironclaw_host_runtime --test runtime_http_egress_contract
• cargo check -p ironclaw_host_runtime -p ironclaw_wasm -p ironclaw_scripts -p ironclaw_mcp --all-targets
• cargo clippy -p ironclaw_host_runtime -p ironclaw_wasm -p ironclaw_scripts -p ironclaw_mcp --all-targets -- -D warnings
• git diff --check

[gemini-code-assist]

Code Review

This pull request enhances security by reordering network policy retrieval to occur before request validation, ensuring one-shot policies are consumed even if validation fails. It also simplifies the WasmRuntimeCredentialRequest struct by removing the network_policy field and adds comprehensive tests for WASM, Script, and MCP adapters to verify policy consumption. I have no further feedback to provide as the existing review comments were purely explanatory.