dev: add parallel dev environment under /docker/dev

Near-1:1 clone of the prod remote-access stack, isolated on a new external
dev_edge network and fronted by the same shared Caddy instance (dual-homed on
edge + dev_edge). Dev is manual-start (not on boot).

- Hostnames: app-dev / api-dev .linumiq.net, tunnels under *.dev.linumiq.net,
  dev tunnel ingress on port 7001.
- Dev Supabase (project supabase-dev, *-dev containers), web, frps, redis,
  stripe-stub, bandwidth-worker with fresh independent secrets (gitignored).
- Shared Caddyfile: app-dev -> web-dev, api-dev -> dev kong (+webhook block),
  *.dev -> frps-dev vhost. Caddy compose dual-homed on dev_edge.
- On-demand-TLS authorizer (prod check-subdomain, in gitignored volumes/)
  extended additively: app-dev/api-dev -> 200; *.dev delegated to the dev
  authorizer. Prod allow-list logic unchanged.
- dev.sh manual up/down/ps helper; README documents topology + secrets.

Secrets, frps.toml, volumes/, web worktree and data dirs are gitignored.

dev/stripe-stub/app.py

@@ -0,0 +1,63 @@
+"""stripe-stub: pretends every checkout succeeds and forwards test webhooks.
+
+Forwarded webhooks are signed with an HMAC-SHA256 signature so the edge
+function can reject unsigned/forged/replayed events.
+"""
+
+import hashlib
+import hmac
+import os
+import time
+import uuid
+from typing import Any
+
+import httpx
+from fastapi import FastAPI, Request
+
+DOMAIN = os.environ.get("DOMAIN", "linumiq.net")
+EDGE_URL = os.environ.get(
+    "EDGE_STRIPE_WEBHOOK_URL",
+    "http://supabase-edge-functions:9000/stripe-webhook",
+)
+WEBHOOK_SECRET = os.environ.get("STRIPE_STUB_WEBHOOK_SECRET", "")
+
+app = FastAPI()
+
+
+def sign(body: bytes) -> str:
+    ts = int(time.time())
+    mac = hmac.new(
+        WEBHOOK_SECRET.encode(),
+        f"{ts}.".encode() + body,
+        hashlib.sha256,
+    ).hexdigest()
+    return f"t={ts},v1={mac}"
+
+
+@app.post("/v1/checkout/sessions")
+async def create_session(_request: Request) -> dict[str, str]:
+    session_id = f"stub_{uuid.uuid4().hex}"
+    return {
+        "id": session_id,
+        "url": f"https://app.{DOMAIN}/billing/success?session={session_id}",
+    }
+
+
+@app.post("/v1/webhooks/test")
+async def forward_test(request: Request) -> Any:
+    body = await request.body()
+    headers = {
+        "content-type": request.headers.get("content-type", "application/json"),
+        "x-stub-signature": sign(body),
+    }
+    async with httpx.AsyncClient(timeout=10.0) as client:
+        resp = await client.post(EDGE_URL, content=body, headers=headers)
+    try:
+        return resp.json()
+    except Exception:
+        return {"upstream_status": resp.status_code, "body": resp.text}
+
+
+@app.get("/health")
+def health() -> dict[str, str]:
+    return {"status": "ok"}