Agents tmux

[jaromil]

Change agent handling, moved everything inside tmux reachable both from terminal and GUI. gestalt-agent now enters tmux and communicates with API.

• Replaced --url with --host + --port.
  • Switched runtime behavior to create external session via API, then execute tmux attach/switch.
  • --dryrun now prints tmux attach command (not codex argv).
  • Files: cmd/gestalt-agent/parse.go, cmd/gestalt-agent/run.go, cmd/gestalt-agent/main.go, cmd/gestalt-agent/exec.go, cmd/gestalt-agent/defaults.go, cmd/gestalt-
  • Added --session-id mode to send stdin directly to /api/sessions/:id/input.
  • Kept agent-resolution path for , still supports --start.
  • Updated completion flags and parsing.
  • Files: cmd/gestalt-send/parse.go, cmd/gestalt-send/main.go, cmd/gestalt-send/http.go, cmd/gestalt-send/completion.go, cmd/gestalt-send/flags_test.go, cmd/
    gestalt-send/main_test.go, cmd/gestalt-send/integration_test.go.
• Docs and orientation updates:
  • API endpoint docs now reflect /api/sessions/:id/input, /api/sessions/:id/activate, and removal of /api/agents/:name/input.
  • CLI docs updated for --host/--port and --session-id.
  • External session and quick-start notes updated for tmux attach flow.
  • AGENTS orientation refreshed for new endpoint/CLI/tmux-hub behavior.
  • Files: docs/reference/http-api.md, docs/reference/cli.md, docs/configuration/agent-configuration.md, docs/external-session-contract.md, docs/getting-started/
    quick-setup.md, AGENTS.md.