refactor: unify peer kind to ChatType, rename dm to direct (#11881)

* fix: use .js extension for ESM imports of RoutePeerKind

The imports incorrectly used .ts extension which doesn't resolve
with moduleResolution: NodeNext. Changed to .js and added 'type'
import modifier.

* fix tsconfig

* refactor: unify peer kind to ChatType, rename dm to direct

- Replace RoutePeerKind with ChatType throughout codebase
- Change 'dm' literal values to 'direct' in routing/session keys
- Keep backward compat: normalizeChatType accepts 'dm' -> 'direct'
- Add ChatType export to plugin-sdk, deprecate RoutePeerKind
- Update session key parsing to accept both 'dm' and 'direct' markers
- Update all channel monitors and extensions to use ChatType

BREAKING CHANGE: Session keys now use 'direct' instead of 'dm'.
Existing 'dm' keys still work via backward compat layer.

* fix tests

* test: update session key expectations for dmdirect migration

- Fix test expectations to expect :direct: in generated output
- Add explicit backward compat test for normalizeChatType('dm')
- Keep input test data with :dm: keys to verify backward compat

* fix: accept legacy 'dm' in session key parsing for backward compat

getDmHistoryLimitFromSessionKey now accepts both :dm: and :direct:
to ensure old session keys continue to work correctly.

* test: add explicit backward compat tests for dmdirect migration

- session-key.test.ts: verify both :dm: and :direct: keys are valid
- getDmHistoryLimitFromSessionKey: verify both formats work

* feat: backward compat for resetByType.dm config key

* test: skip unix-path Nix tests on Windows

src/routing/session-key.ts

@@ -1,3 +1,4 @@
+import type { ChatType } from "../channels/chat-type.js";
 import { parseAgentSessionKey, type ParsedAgentSessionKey } from "../sessions/session-key-utils.js";
 
 export {
@@ -140,14 +141,14 @@ export function buildAgentPeerSessionKey(params: {
   mainKey?: string | undefined;
   channel: string;
   accountId?: string | null;
-  peerKind?: "dm" | "group" | "channel" | null;
+  peerKind?: ChatType | null;
   peerId?: string | null;
   identityLinks?: Record<string, string[]>;
   /** DM session scope. */
   dmScope?: "main" | "per-peer" | "per-channel-peer" | "per-account-channel-peer";
 }): string {
-  const peerKind = params.peerKind ?? "dm";
-  if (peerKind === "dm") {
+  const peerKind = params.peerKind ?? "direct";
+  if (peerKind === "direct") {
     const dmScope = params.dmScope ?? "main";
     let peerId = (params.peerId ?? "").trim();
     const linkedPeerId =
@@ -165,14 +166,14 @@ export function buildAgentPeerSessionKey(params: {
     if (dmScope === "per-account-channel-peer" && peerId) {
       const channel = (params.channel ?? "").trim().toLowerCase() || "unknown";
       const accountId = normalizeAccountId(params.accountId);
-      return `agent:${normalizeAgentId(params.agentId)}:${channel}:${accountId}:dm:${peerId}`;
+      return `agent:${normalizeAgentId(params.agentId)}:${channel}:${accountId}:direct:${peerId}`;
     }
     if (dmScope === "per-channel-peer" && peerId) {
       const channel = (params.channel ?? "").trim().toLowerCase() || "unknown";
-      return `agent:${normalizeAgentId(params.agentId)}:${channel}:dm:${peerId}`;
+      return `agent:${normalizeAgentId(params.agentId)}:${channel}:direct:${peerId}`;
     }
     if (dmScope === "per-peer" && peerId) {
-      return `agent:${normalizeAgentId(params.agentId)}:dm:${peerId}`;
+      return `agent:${normalizeAgentId(params.agentId)}:direct:${peerId}`;
     }
     return buildAgentMainSessionKey({
       agentId: params.agentId,