feat: loadable openclaw channel plugin v1 (agent=account)

Rewritten against the real openclaw v2026.5.7 plugin SDK (generic
third-party channel path): createChannelPluginBase + createChatChannelPlugin
with required capabilities, minimal ChannelSetupAdapter, agent=account
config resolution, attached outbound -> Fabric POST, inbound socket per
account -> runtime.channel.turn (wakeup->admission). Compat notes mark
SDK-coupled seams for future openclaw upgrades. Verified: builds clean,
installs, 'openclaw channels list' -> Fabric installed/configured/enabled.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dist/fabric/src/accounts.js

@@ -0,0 +1,41 @@
+// agent = openclaw channel account.
+// Config shape:
+//   channels.fabric.centerApiBase = "http://localhost:7001/api"   (shared)
+//   channels.fabric.accounts.<agentId> = { fabricApiKey, centerApiBase? }
+// Each account id IS the openclaw agentId that owns that Fabric identity.
+const DEFAULT_CENTER = 'http://localhost:7001/api';
+function section(cfg) {
+    return cfg.channels?.fabric ?? {};
+}
+export function listFabricAccountIds(cfg) {
+    const accts = section(cfg).accounts ?? {};
+    const ids = Object.keys(accts);
+    return ids.length ? ids : ['default'];
+}
+export function resolveDefaultFabricAccountId(cfg) {
+    const s = section(cfg);
+    if (s.defaultAccount)
+        return s.defaultAccount;
+    const ids = listFabricAccountIds(cfg);
+    return ids[0] ?? 'default';
+}
+export function resolveFabricAccount(cfg, accountId) {
+    const s = section(cfg);
+    const id = accountId ?? resolveDefaultFabricAccountId(cfg);
+    const acc = s.accounts?.[id] ?? {};
+    const fabricApiKey = (acc.fabricApiKey ?? '').trim();
+    const centerApiBase = (acc.centerApiBase ?? s.centerApiBase ?? DEFAULT_CENTER).trim();
+    return {
+        accountId: id,
+        enabled: acc.enabled !== false && s.enabled !== false,
+        centerApiBase,
+        fabricApiKey,
+        allowFrom: acc.allowFrom ?? s.allowFrom ?? [],
+        dmPolicy: acc.dmPolicy ?? s.dmPolicy,
+    };
+}
+export function listEnabledFabricAccounts(cfg) {
+    return listFabricAccountIds(cfg)
+        .map((id) => resolveFabricAccount(cfg, id))
+        .filter((a) => a.enabled && a.fabricApiKey);
+}