Add Fly.io public reverse proxy for docs.eblu.me (#120)

## Summary

- Adds a Fly.io reverse proxy (`blumeops-proxy`) that tunnels public traffic to homelab services over Tailscale
- First service exposed: `docs.eblu.me` — the Quartz static docs site
- Includes Pulumi IaC for Tailscale auth key/ACLs and Gandi DNS CNAME
- Adds mise tasks (`fly-deploy`, `fly-setup`, `fly-shutoff`) and Forgejo CI workflow

## Key details

- Fly.io Firecracker VMs support TUN devices natively — no userspace networking needed
- Tailscale auth key is `preauthorized=True` to avoid device approval hangs on container restarts
- nginx caches aggressively for the static site; health check is on the default_server block
- ACLs restrict `tag:flyio-proxy` to `tag:k8s` on port 443 only
- DNS CNAME deployed and verified: `docs.eblu.me` → `blumeops-proxy.fly.dev`

## Test plan

- [x] `curl -sf https://blumeops-proxy.fly.dev/healthz` returns `ok`
- [x] `curl -I -H "Host: docs.eblu.me" https://blumeops-proxy.fly.dev/` returns 200 with `X-Cache-Status`
- [x] `curl -I https://docs.eblu.me/` returns 200 with valid Let's Encrypt cert
- [x] `dig forge.ops.eblu.me` still resolves to 100.98.163.89 (private services unaffected)
- [x] Set `FLY_DEPLOY_TOKEN` Forgejo Actions secret for CI auto-deploy

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/120

fly/nginx.conf

@@ -0,0 +1,61 @@
+worker_processes auto;
+
+events {
+    worker_connections 1024;
+}
+
+http {
+    include /etc/nginx/mime.types;
+    default_type application/octet-stream;
+
+    # Rate limiting zones — define per-service zones as needed
+    limit_req_zone $binary_remote_addr zone=general:10m rate=10r/s;
+
+    # Proxy cache: 200MB, evict after 24h of no access
+    proxy_cache_path /tmp/cache levels=1:2 keys_zone=services:10m
+                     max_size=200m inactive=24h;
+
+    # --- docs.eblu.me (static site) ---
+    server {
+        listen 8080;
+        server_name docs.eblu.me;
+
+        limit_req zone=general burst=20 nodelay;
+
+        location / {
+            proxy_pass https://docs.tail8d86e.ts.net;
+            proxy_ssl_verify off;
+            proxy_ssl_server_name on;
+
+            # Cache aggressively — static site only.
+            # Do NOT use these settings for dynamic services.
+            proxy_cache services;
+            proxy_cache_valid 200 1d;
+            proxy_cache_valid 404 1m;
+            proxy_cache_use_stale error timeout updating;
+            proxy_cache_lock on;
+
+            # Prevent cache-busting: ignore query strings and
+            # client cache-control headers.
+            # Safe for static sites; breaks dynamic services.
+            proxy_cache_key $host$uri;
+            proxy_ignore_headers Cache-Control Set-Cookie;
+
+            add_header X-Cache-Status $upstream_cache_status;
+        }
+
+    }
+
+    # Catch-all: reject unknown hosts, but serve health check
+    server {
+        listen 8080 default_server;
+
+        location /healthz {
+            return 200 "ok\n";
+        }
+
+        location / {
+            return 444;
+        }
+    }
+}