chore(knip): add config and remove dead code/deps

- knip.json: scope to src, ignore submodule/worktrees, mark
  generated abi.ts as unresolved-allowed, honor @public JSDoc tag
- drop 14 orphaned files (12 ui components, model/Bank, model/Pix)
- drop 18 unused deps (urql, tanstack, wagmi/{core,vue}, graphql,
  permissionless, graphql-codegen suite, axe-core, lighthouse,
  vue/test-utils)
- drop 4 unused exports and de-export 9 internal-only types
- mark NetworksTestnet as @public (in-flight testnet support)

knip.json

@@ -0,0 +1,22 @@
+{
+  "$schema": "https://unpkg.com/knip@latest/schema.json",
+  "entry": [
+    "src/router/index.ts",
+    "index.html",
+    "wagmi.config.ts"
+  ],
+  "project": [
+    "src/**/*.{ts,vue}",
+    "*.config.{ts,js}"
+  ],
+  "ignore": [
+    "p2pix-smart-contracts/**",
+    ".claude/**",
+    "babel.config.js"
+  ],
+  "ignoreUnresolved": [
+    "./abi",
+    "@/blockchain/abi"
+  ],
+  "tags": ["public"]
+}