Set up Firestore structure for mana bounty links

common/manalink.ts

@@ -0,0 +1,27 @@
+export type Manalink = {
+  // The link to send: https://manifold.markets/send/{slug}
+  // Also functions as the unique identifier for the link.
+  slug: string
+
+  // Note: we assume both fromId and toId are of SourceType 'USER'
+  fromId: string
+
+  // How much to send with the link
+  amount: number
+  token: 'M$' // TODO: could send eg YES shares too??
+
+  createdTime: number
+  // If not set, the link is valid forever
+  expiresTime?: number
+  // If not set, the link can be used infinitely
+  maxUses?: number
+
+  // All past usages of this link
+  claims: Claim[]
+}
+
+type Claim = {
+  toId: string
+
+  claimedTime: number
+}