refactor: extract connection state

[zatevakhin]

change

• extract the five application-owned connection fields into private ConnectionState
• move ConnState and ServerState into the owner while keeping ConnectionEvent, ServerEvent, runtime retry policy, transport, channels, endpoint selection, and process supervision at their existing boundaries
• preserve connection/server event ordering, exact status strings, reconnect commands, launch-cwd precedence, command guards, and the three-state indicator
• add focused owner, app coordinator, server-event, handler, and ui tests

exact base and scope

• base commit: b8237b6959c44ad3f5d8486107c595add7dd326b
• base parent: 3a7a599ff0fb04def35f2ba1591d3623dc5e9ba0
• base tree: c6ce4018b275f14e5eee0fb54d92ad8ed04c9f4d
• source commit: d8ad276
• target: refactor/components
• changed exactly the 11 approved source files: src/connection_state.rs, src/lib.rs, src/app.rs, src/server_manager.rs, src/runtime/endpoint.rs, src/runtime/mod.rs, src/runtime/event_loop.rs, src/handlers.rs, src/session.rs, src/acp_state.rs, and src/ui/mod.rs
• diff: 508 insertions, 191 deletions

validation

• cargo fmt --all -- --check
• cargo check --all-targets --all-features
• cargo clippy --all-targets --all-features -- -D warnings
• cargo build --all-targets --all-features
• cargo test --all-targets --all-features — 859 passed, 0 failed (base: 848)
• git diff --check
• focused owner, app connection-event, command-guard, server-event suppression/status, endpoint, reconnect/launch-cwd, and ui indicator tests passed

boundary proof

• one private mod connection_state;; no export or re-export
• one App.connection: ConnectionState; owner has exactly five fields; App has 63 direct fields
• one definition each of ConnectionState, ConnState, and ServerState
• no flat App declarations or accesses for the extracted fields; no getter/facade/alias/Deref/second owner
• ConnectionEvent remains in app; ServerEvent remains in server_manager; ConnectionManagerEvent and ServerChannelMsg remain in runtime
• runtime backoff remains in runtime/connection.rs; ACP runtime launch cwd remains in acp_client.rs
• 52 Rust files, 44,822 Rust lines, five App implementation files, and four phase 11 compatibility forward tags
• AGENTS.md, CLAUDE.md, REFACTOR.md, roadmap/history, runtime retry, transport, config, protocol, and domain files are absent from the source commit

integration into refactor/components is still pending review and merge.