Add unsafe raw-nsec login fallback

Collapsed-by-default 'paste an nsec (unsafe)' option on the login screen,
signs the NIP-98 login event client-side with nostr-tools and never
persists the key (used once in memory, discarded) — for testing/kiosk
use without a NIP-07 extension. Clearly labeled as unsafe in the UI.

frontend/package-lock.json

@@ -9,6 +9,7 @@
       "version": "0.1.0",
       "dependencies": {
         "leaflet": "^1.9.4",
+        "nostr-tools": "^2.24.1",
         "pinia": "^3.0.0",
         "vue": "^3.5.0"
       },
@@ -579,6 +580,45 @@
         "node": "^22.20 || ^24.12 || >=25"
       }
     },
+    "node_modules/@noble/ciphers": {
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/@noble/ciphers/-/ciphers-2.1.1.tgz",
+      "integrity": "sha512-bysYuiVfhxNJuldNXlFEitTVdNnYUc+XNJZd7Qm2a5j1vZHgY+fazadNFWFaMK/2vye0JVlxV3gHmC0WDfAOQw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 20.19.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
+    "node_modules/@noble/curves": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/@noble/curves/-/curves-2.0.1.tgz",
+      "integrity": "sha512-vs1Az2OOTBiP4q0pwjW5aF0xp9n4MxVrmkFBxc6EKZc6ddYx5gaZiAsZoq0uRRXWbi3AT/sBqn05eRPtn1JCPw==",
+      "license": "MIT",
+      "dependencies": {
+        "@noble/hashes": "2.0.1"
+      },
+      "engines": {
+        "node": ">= 20.19.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
+    "node_modules/@noble/hashes": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/@noble/hashes/-/hashes-2.0.1.tgz",
+      "integrity": "sha512-XlOlEbQcE9fmuXxrVTXCTlG2nlRXa9Rj3rr5Ue/+tX+nmkgbX720YHh0VR3hBF9xDvwnb8D2shVGOwNx+ulArw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 20.19.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
     "node_modules/@nodelib/fs.scandir": {
       "version": "2.1.5",
       "resolved": "https://registry.npmjs.org/@nodelib/fs.scandir/-/fs.scandir-2.1.5.tgz",
@@ -974,6 +1014,42 @@
         "win32"
       ]
     },
+    "node_modules/@scure/base": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/@scure/base/-/base-2.0.0.tgz",
+      "integrity": "sha512-3E1kpuZginKkek01ovG8krQ0Z44E3DHPjc5S2rjJw9lZn3KSQOs8S7wqikF/AH7iRanHypj85uGyxk0XAyC37w==",
+      "license": "MIT",
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
+    "node_modules/@scure/bip32": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/@scure/bip32/-/bip32-2.0.1.tgz",
+      "integrity": "sha512-4Md1NI5BzoVP+bhyJaY3K6yMesEFzNS1sE/cP+9nuvE7p/b0kx9XbpDHHFl8dHtufcbdHRUUQdRqLIPHN/s7yA==",
+      "license": "MIT",
+      "dependencies": {
+        "@noble/curves": "2.0.1",
+        "@noble/hashes": "2.0.1",
+        "@scure/base": "2.0.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
+    "node_modules/@scure/bip39": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/@scure/bip39/-/bip39-2.0.1.tgz",
+      "integrity": "sha512-PsxdFj/d2AcJcZDX1FXN3dDgitDDTmwf78rKZq1a6c1P1Nan1X/Sxc7667zU3U+AN60g7SxxP0YCVw2H/hBycg==",
+      "license": "MIT",
+      "dependencies": {
+        "@noble/hashes": "2.0.1",
+        "@scure/base": "2.0.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
     "node_modules/@types/estree": {
       "version": "1.0.9",
       "resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.9.tgz",
@@ -1902,6 +1978,35 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/nostr-tools": {
+      "version": "2.24.1",
+      "resolved": "https://registry.npmjs.org/nostr-tools/-/nostr-tools-2.24.1.tgz",
+      "integrity": "sha512-KdrKjC74n/rr6J3eCSfZj8dcbZFvolHYe4S22SefNZ5YWbhHiB0KL/mmJjEZ0u6B9mZK0YcQtl+WQ46KzwapeQ==",
+      "license": "Unlicense",
+      "dependencies": {
+        "@noble/ciphers": "2.1.1",
+        "@noble/curves": "2.0.1",
+        "@noble/hashes": "2.0.1",
+        "@scure/base": "2.0.0",
+        "@scure/bip32": "2.0.1",
+        "@scure/bip39": "2.0.1",
+        "nostr-wasm": "0.1.0"
+      },
+      "peerDependencies": {
+        "typescript": ">=5.0.0"
+      },
+      "peerDependenciesMeta": {
+        "typescript": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/nostr-wasm": {
+      "version": "0.1.0",
+      "resolved": "https://registry.npmjs.org/nostr-wasm/-/nostr-wasm-0.1.0.tgz",
+      "integrity": "sha512-78BTryCLcLYv96ONU8Ws3Q1JzjlAt+43pWQhIl86xZmWeegYCNLPml7yQ+gG3vR6V5h4XGj+TxO+SS5dsThQIA==",
+      "license": "MIT"
+    },
     "node_modules/object-assign": {
       "version": "4.1.1",
       "resolved": "https://registry.npmjs.org/object-assign/-/object-assign-4.1.1.tgz",