Bsky link card service (#4547)

* setup bskycard

* quick proof of concept for png card generation

* bskycard: use jsx

* bskycard: 3x5 profile layout

* bskycard: add butterfly overlay

* bskycard: tidy

* bskycard: separate and reorganize

* bskycard: tidy

* bskycard: tidy

* bskycard: tidy

* bskycard: poc of transparent overlay and box shadow

* bskycard: reorg impl into src/ directory

* bskycard: use more standard app structure

* bskycard: setup dockerfile, fix build

* bskycard: support for x-origin-verify

* bskycard: card layout, filter images based on labels

* bskycard: tidy

* bskycard: support cluster mode

* bskycard: handle error fetching starter pack info

* bskycard: tidy

* bskycard: fix leak on failed image fetch

* bskycard: build workflow

* bskyogcard: rename from bskycard

* bskyogcard: fix some express plumbing

* bskyogcard: add cdn tags, tidy

bskyogcard/src/config.ts

@@ -0,0 +1,40 @@
+import {envInt, envStr} from '@atproto/common'
+
+export type Config = {
+  service: ServiceConfig
+}
+
+export type ServiceConfig = {
+  port: number
+  version?: string
+  appviewUrl: string
+  originVerify?: string
+}
+
+export type Environment = {
+  port?: number
+  version?: string
+  appviewUrl?: string
+  originVerify?: string
+}
+
+export const readEnv = (): Environment => {
+  return {
+    port: envInt('CARD_PORT'),
+    version: envStr('CARD_VERSION'),
+    appviewUrl: envStr('CARD_APPVIEW_URL'),
+    originVerify: envStr('CARD_ORIGIN_VERIFY'),
+  }
+}
+
+export const envToCfg = (env: Environment): Config => {
+  const serviceCfg: ServiceConfig = {
+    port: env.port ?? 3000,
+    version: env.version,
+    appviewUrl: env.appviewUrl ?? 'https://api.bsky.app',
+    originVerify: env.originVerify,
+  }
+  return {
+    service: serviceCfg,
+  }
+}