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/bitvid-compat/src/profile.js

@@ -1,7 +1,7 @@
 // Reference application profile for the extraction's characterization corpus.
 //
 // These values are one application's configuration, not governance defaults.
-// They live outside @nostr-governance/core on purpose: the core engine must
+// They live outside @bitgate/core on purpose: the core engine must
 // carry no application thresholds, and this file is what proves the generic
 // engine can reproduce a real deployment's behavior.
 //
@@ -9,7 +9,7 @@
 // docs/reference-map.md). Changing a number here should break a conformance
 // fixture — that is the point.
 
-import { createPolicyDefinition } from "@nostr-governance/core";
+import { createPolicyDefinition } from "@bitgate/core";
 
 /** Trusted reports needed before a thumbnail is blurred. */
 export const BLUR_THRESHOLD = 3;
@@ -34,7 +34,7 @@ export const TRUSTED_MUTE_WINDOW_SECONDS = TRUSTED_MUTE_WINDOW_DAYS * 24 * 60 *
  * autoplay threshold is the withheld autoplay. Spam escalates to a hide at its
  * own higher threshold, while other categories never hide on reports alone.
  *
- * @type {Record<string, import('@nostr-governance/core').CategoryThresholds>}
+ * @type {Record<string, import('@bitgate/core').CategoryThresholds>}
  */
 const REPORT_THRESHOLDS = {
   default: {
@@ -54,7 +54,7 @@ const REPORT_THRESHOLDS = {
  * Below the hide threshold a trusted mute is a ranking signal only: it must not
  * blur, must not block playback, and must not read as an administrative denial.
  *
- * @type {Record<string, import('@nostr-governance/core').CategoryThresholds>}
+ * @type {Record<string, import('@bitgate/core').CategoryThresholds>}
  */
 const MUTE_THRESHOLDS = {
   default: {
@@ -70,7 +70,7 @@ const MUTE_THRESHOLDS = {
  * override: discovery feeds decline to hard-hide so that a single stale list
  * cannot empty a feed, while playback enforces the full decision.
  *
- * @type {import('@nostr-governance/core').PolicyDefinition}
+ * @type {import('@bitgate/core').PolicyDefinition}
  */
 export const REFERENCE_POLICY = createPolicyDefinition({
   id: "reference-video-app",