feat: rename to BitGate and close the drop-in gap

Renames the project and makes it as easy to adopt as BitLogin, which was the
stated bar and which it did not previously meet.

Rename (ADR 0005): @nostr-governance/* -> @bitgate/*, governance-* elements ->
bitgate-*, createGovernanceRuntime -> createBitGate. "Governance" reads as DAO
voting to this audience and named a category rather than a product; BitGate
names the benefit and joins the bit- family that BitVid and BitRoad compose
with. Domain types keep their names — the product is BitGate, the subject
matter is still governance. The migration plan is left as written; this ADR
records the change rather than rewriting history.

Drop-in distribution (ADR 0006): adopting BitGate meant supplying a transport,
authoring a policy, and wiring every element in JavaScript. Now:

- createRelayTransport(urls) — WebSocket transport with reconnection, backoff,
  subscription replay, and cross-relay dedupe
- policy presets (social, commerce, admin-only) addressable by name; the engine
  still carries no thresholds of its own
- <bitgate-provider> — configuration in markup, with descendants finding the
  runtime through a bubbling context event rather than DOM walking, which
  breaks across shadow boundaries
- npm run build:widget — a self-contained dist/bitgate.js

That last one came from running it in a browser rather than from a test. Bare
specifiers resolve in Node and vitest but not in a browser, so the widget
source worked everywhere except a plain static page — the one place it exists
to serve. The bundle is not committed: consumers build from reviewed source.

Also found by running it: the provider's ready event fires during element
upgrade, before a page that defines elements after parsing can attach a
listener, so it now exposes `ready` as a promise too.

Four bugs fixed along the way, three found by new tests and one by the browser:
admin state stayed silent when a roster change altered capabilities but no
denials; the relay transport sent every subscription twice on connect; the
commerce preset computed a meaningless visibility verdict at checkout and could
hide a listing from its own seller; <bitgate-status> threw on an unusable
decision.

759 tests; lint, typecheck, and both builds clean.

packages/runtime/src/stores.js

@@ -11,17 +11,17 @@ import {
   normalizePubkey,
   reduceAdminState,
   serializeAdminState,
-} from "@nostr-governance/core";
-import { selectReplaceable, toMuteRecords } from "@nostr-governance/nostr";
+} from "@bitgate/core";
+import { selectReplaceable, toMuteRecords } from "@bitgate/nostr";
 
 import { Emitter } from "./emitter.js";
 
 /**
- * @typedef {import('@nostr-governance/core').PolicyDefinition} PolicyDefinition
- * @typedef {import('@nostr-governance/core').Contribution} Contribution
- * @typedef {import('@nostr-governance/core').AuthorityState} AuthorityState
- * @typedef {import('@nostr-governance/core').AdminState} AdminState
- * @typedef {import('@nostr-governance/nostr').NostrEvent} NostrEvent
+ * @typedef {import('@bitgate/core').PolicyDefinition} PolicyDefinition
+ * @typedef {import('@bitgate/core').Contribution} Contribution
+ * @typedef {import('@bitgate/core').AuthorityState} AuthorityState
+ * @typedef {import('@bitgate/core').AdminState} AdminState
+ * @typedef {import('@bitgate/nostr').NostrEvent} NostrEvent
  */
 
 /**
@@ -248,7 +248,7 @@ export class ReportStore extends Emitter {
    * The target is identified by `targetKey`; a decoded report's own `target`
    * field is accepted but not required, since it would be redundant.
    *
-   * @param {{ reporter: string, category: string, createdAt?: number, target?: import('@nostr-governance/core').GovernanceTarget }} report
+   * @param {{ reporter: string, category: string, createdAt?: number, target?: import('@bitgate/core').GovernanceTarget }} report
    * @param {string} targetKey
    */
   ingest(report, targetKey) {
@@ -349,7 +349,7 @@ export class TrustedMuteStore extends Emitter {
    * A newer list fully replaces the older one; an out-of-order delivery of an
    * older list is ignored rather than resurrecting removed entries.
    *
-   * @param {import('@nostr-governance/nostr').DecodedMuteList} list
+   * @param {import('@bitgate/nostr').DecodedMuteList} list
    */
   replaceList(list) {
     if (!list?.owner) {