feat(verify): optional NIP-01 signature verification, on by default in the widget

Closes the gap the audit left open: administrative state fails closed without a
verifier, and BitGate shipped none.

@bitgate/verify is a separate package so core, nostr, and runtime keep no crypto
dependency and can be audited without one. The widget bundles it, so the
drop-in path is verified with no extra step; verify="off" disables it, sets
data-unverified on the element, and emits bitgate:unverified — meant for local
development, and meant to be visible.

Verification recomputes the event id before checking the signature. Checking
only the signature would let a forged event pass by reusing a genuine signature
over an unrelated id, which is the failure mode that matters here.

createVerifier also rejects events dated far in the future. A far-future
created_at wins replaceable-event selection indefinitely and pins stale state in
place; the signature is perfectly valid, so only a clock check catches it.

Found while testing: #adminIngestAllowed checked that a verifier *exists*, not
that this event was verified — so the public ingestEvent path, which
"bring your own relays" integrations use, bypassed verification entirely.
Verification now runs inside ingestEvent, with an already-verified flag for the
loaders. An async verifier cannot be awaited there and is treated as
unverified; ingestVerified() awaits properly.

Conformance validated against 120 live events from a public relay across kinds
0, 1, 3 and 10002 — 59 with non-ASCII content and 71 containing quotes,
newlines or tabs, which is where a serialization mismatch would surface. All
120 verified, zero id mismatches.

Bundle grows 72K -> 120K. 855 tests; audit clean.

package-lock.json

@@ -58,6 +58,10 @@
       "resolved": "packages/testing",
       "link": true
     },
+    "node_modules/@bitgate/verify": {
+      "resolved": "packages/verify",
+      "link": true
+    },
     "node_modules/@bitgate/widget": {
       "resolved": "packages/widget",
       "link": true
@@ -528,6 +532,33 @@
         "node": "^22.20 || ^24.12 || >=25"
       }
     },
+    "node_modules/@noble/curves": {
+      "version": "1.9.7",
+      "resolved": "https://registry.npmjs.org/@noble/curves/-/curves-1.9.7.tgz",
+      "integrity": "sha512-gbKGcRUYIjA3/zCCNaWDciTMFI0dCkvou3TL8Zmy5Nc7sJ47a0jtOeZoTaMxkuqRo9cRhjOdZJXegxYE5FN/xw==",
+      "license": "MIT",
+      "dependencies": {
+        "@noble/hashes": "1.8.0"
+      },
+      "engines": {
+        "node": "^14.21.3 || >=16"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
+    "node_modules/@noble/hashes": {
+      "version": "1.8.0",
+      "resolved": "https://registry.npmjs.org/@noble/hashes/-/hashes-1.8.0.tgz",
+      "integrity": "sha512-jCs9ldd7NwzpgXDIf6P3+NrHh9/sD6CQdxHyjQI+h/6rDNo88ypBxxz45UDuZHz9r3tNz7N/VInSVoVdtXEI4A==",
+      "license": "MIT",
+      "engines": {
+        "node": "^14.21.3 || >=16"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
     "node_modules/@rollup/rollup-android-arm-eabi": {
       "version": "4.62.4",
       "resolved": "https://registry.npmjs.org/@rollup/rollup-android-arm-eabi/-/rollup-android-arm-eabi-4.62.4.tgz",
@@ -1813,12 +1844,21 @@
         "@bitgate/core": "*"
       }
     },
+    "packages/verify": {
+      "name": "@bitgate/verify",
+      "version": "0.1.0",
+      "dependencies": {
+        "@noble/curves": "^1.9.0",
+        "@noble/hashes": "^1.8.0"
+      }
+    },
     "packages/widget": {
       "name": "@bitgate/widget",
       "version": "0.1.0",
       "dependencies": {
         "@bitgate/core": "*",
-        "@bitgate/runtime": "*"
+        "@bitgate/runtime": "*",
+        "@bitgate/verify": "*"
       }
     }
   }