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/routes/util.ts

@@ -0,0 +1,36 @@
+import {ErrorRequestHandler, Request, RequestHandler, Response} from 'express'
+
+import {AppContext} from '../context.js'
+import {httpLogger} from '../logger.js'
+
+export type Handler = (req: Request, res: Response) => Awaited<void>
+
+export const handler = (runHandler: Handler): RequestHandler => {
+  return async (req, res, next) => {
+    try {
+      await runHandler(req, res)
+    } catch (err) {
+      next(err)
+    }
+  }
+}
+
+export function originVerifyMiddleware(ctx: AppContext): RequestHandler {
+  const {originVerify} = ctx.cfg.service
+  if (!originVerify) return (_req, _res, next) => next()
+  return (req, res, next) => {
+    const verifyHeader = req.headers['x-origin-verify']
+    if (verifyHeader !== originVerify) {
+      return res.status(404).end('not found')
+    }
+    next()
+  }
+}
+
+export const errorHandler: ErrorRequestHandler = (err, req, res, next) => {
+  httpLogger.error({err}, 'request error')
+  if (res.headersSent) {
+    return next(err)
+  }
+  return res.status(500).end('server error')
+}