Add an opt-in, capped AI-client telnet port (engine primitives for an AI playtest harness)

[pruuk]

Summary

I'd like to add a small set of opt-in, disabled-by-default engine primitives
that enable a dedicated telnet port for AI/test clients: a separate listener, an
independent connection cap, per-round command rate limiting, ANSI-stripped
output, and a persisted IsAI flag on user records. With default config this is
a no-op — nothing changes for a stock server until an operator sets a port.

This is the engine slice of a generalized AI playtest harness I'm building
for GoMud (point an AI agent at your server, have it play through operator-defined
goals using standard tester "personalities," and emit a report). I gave a heads-up
on Discord that this was coming; opening this issue to get agreement on the
engine-side change as an actionable item before I send the PR.

Why this needs to live in the engine (not a module)

A dedicated, bounded port for AI traffic can't be delivered as a registry module:
the second net.Listener, a connection-type tag on ConnectionDetails, a
per-type cap, output shaping in Write, and an input-loop rate gate all sit
below the plugin/module API. Everything above that line (account provisioning,
sandbox/safe-mode, flagging commands) will ship as a separate, opt-in community
module — none of it is proposed here.

Proposed primitives (the whole scope)

1. Network.AIPort (0 = disabled), Network.MaxAIConnections (default 20),
   Network.AICommandsPerRound (default 2), following the existing SSHPort
   "0 disables" convention. Shipped disabled in config.yaml.
2. A ConnType (ConnHuman/ConnAI) on ConnectionDetails, set at accept time.
3. A dedicated AI listener that opens only when AIPort > 0, with an independent
   connection cap.
4. ANSI stripping on output for AI connections (telnet IAC preserved).
5. A per-round command rate limiter for AI connections.
6. A persisted UserRecord.IsAI bool flag — the reusable primitive that policy
   code (e.g. leaderboard exclusion) can filter on.

Explicitly out of scope (lives in a separate module)

• Account auto-provisioning, safe-mode / sandbox confinement, IsAI flagging
  commands, leaderboard changes.

Compatibility

• Disabled by default → no behavior change for existing servers.
• connections.Add(...) gains a variadic connType, so existing callers
  compile unchanged.
• Thin diff, primitives only, unit-tested (testify).

Question for maintainers

Is this acceptable as an actionable item, and is the scope/shape right before I
open the PR? Happy to adjust naming, defaults, or split it further. The PR is
ready to go pending agreement here.

[pruuk]

See the repo here: https://github.com/pruuk/gomud-playtest-harness/tree/main

All of the work is done and tested that I can do without sending PRs.

[Volte6]

My only suggestion would be possibly to put "AI" into its own namespace...
Network.AI.Port
Network.AI.MaxConnections
Network.AI.CommandsPerRound

[pruuk]

#601
#602

2 PRs added. I refactored to give AI it's own namespace (good suggestion). If and when these PRs are accepted, I'll publish the module and send a 3rd PR to the module repo to register the play tester agent harness module