Track upstream ACP session injection dependencies #25

Kit ships ACP v2 session injection through published fork crates while the protocol and SDK work is reviewed upstream. Kit no longer depends on any git revision (#256).

Upstream work

• RFD: docs(rfd): mid-turn input via session/inject (queue and steer) agentclientprotocol/agent-client-protocol#1261
• Protocol schema: feat(unstable-v2): add session injection schema agentclientprotocol/agent-client-protocol#2043
• Rust SDK response receipts: feat(jsonrpc): add tracked response receipts agentclientprotocol/rust-sdk#338
• Rust SDK injection support: feat(unstable-v2): add session injection support agentclientprotocol/rust-sdk#339
• AgentKit ACP v2 foundation: feat(acp): add opt-in ACP v2 runtime foundation danielkov/agentkit#12
• AgentKit injection implementation: feat(acp): release ACP v2 session injection behind unstable-inject danielkov/agentkit#31 (supersedes feat(acp): add unstable v2 session injection danielkov/agentkit#13), released as agentkit-acp 0.10.12 behind unstable-inject

Kit follow-up

• Replace the git pins with released crates (chore(deps): use published ACP and agentkit forks instead of git pins #256)
• Remove the temporary [patch] entries (chore(deps): use published ACP and agentkit forks instead of git pins #256)
• Resolve all ACP and AgentKit packages to one source identity (chore(deps): use published ACP and agentkit forks instead of git pins #256)
• Switch from the fork crates to upstream releases once the schema and SDK work above ships
• Re-pin macos/ACP/Schema to the upstream schema at the same time

Current fork crates

The forks keep the upstream library names (agent_client_protocol, agent_client_protocol_schema, agent_client_protocol_http). Switching back should only need changes to Cargo.toml.

The schema fork is based on v1.9.1, not upstream main, because upstream SDK main still pins schema =1.9.1: schema 1.10 removes MCP connect types the SDK uses.