feat(agent): MCP server support and session modes

- Build MCP server configs for HTTP/SSE/Stdio with bearer token extraction\n- Include modes in load_session response with improved errors\n- Wire mcp_servers into session config and timeouts

refactor(commands): split handlers; simplify background tasks

- New handlers for new/status/model/approvals/quit\n- Return Option<Op>; avoid error propagation during chunk send\n- Remove unused local fs write helpers

chore(deps): bump agent-client-protocol to 0.4.7

chore: bump crate version to 0.1.5

bump acp version and add Plan event msg implementation

Merge pull request #10 from agamblin/feature/acp-filesystem

feat(acp): implemented acp read and write files protocols

opt: format the status cmd output

opt: format the status cmd output

Merge pull request #7 from cola-io/fix-session-mode

fix: set session mode