Introduce src/config/terminal-history.ts: one place for terminal scrollback,
tmux history-limit, and PTY buffer byte caps, each overridable via env var or
the settings object and bounds-clamped via resolveTerminalHistoryConfig().
Defaults match the prior hardcoded values, so this is behavior-neutral. Wires
the resolver through buffer-limits, tmux-manager (incl. a setHistoryLimit so a
settings change applies live), session, server, system-routes, session-routes,
schemas, and the config port. Adds 4 optional settings keys (terminalScrollback
Lines, tmuxHistoryLimit, terminalBufferMaxBytes, terminalBufferTrimBytes) with
bounds + a trim<=max cross-check.
Split 6,710-line server.ts into focused route modules using port
interfaces for dependency injection. 107/109 routes extracted into
12 domain files with auth middleware, 5 port interfaces, and shared
helpers. Server.ts retains orchestration (SSE, lifecycle, state).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>