fix(cinny-nginx): give content-hashed app files their own rate budget

A cold page load fires ~75 requests within a second and the service worker
precaches all ~126 build files at once (every deploy renames them), both
past chat_limit's burst of 60. The excess got 503 "limiting requests":
a fresh visit to /register/matrix.org rendered blank (4 chunks refused),
and precache installs could fail after deploys. Like decorations (matrix
#22), hashed js/css/fonts/images/wasm now use assets_limit (100 r/s,
burst 400); pages and the webhook keep chat_limit. The deploy validates
with nginx -t and restores the old config on failure.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

cinny/nginx.conf

@@ -17,6 +17,14 @@ map $uri $lotus_shell_cache_control {
 # decoration picker can fetch hundreds of thumbnails, which would otherwise use
 # up chat_limit and 503 the app's own files.
 limit_req_zone $binary_remote_addr zone=decorations_limit:10m rate=100r/s;
+#
+# [cinny #201 follow-up] Content-hashed app files (js/css/fonts/images/wasm)
+# likewise: a cold page load fires ~75 requests within a second, and the
+# service worker precaches all ~126 build files at once (every deploy renames
+# them), both past chat_limit's burst of 60, so chunks 503ed and pages
+# rendered blank / the precache install failed. Immutable files, cheap to
+# serve; pages and the webhook keep chat_limit.
+limit_req_zone $binary_remote_addr zone=assets_limit:10m rate=100r/s;
 
 server {
     listen 80;
@@ -85,6 +93,8 @@ server {
         }
         location ~* \.(?:js|css|woff2?|png|svg|ico|webp|wasm)$ {
             include snippets/cinny-security-headers-framed.conf;
+            # Own budget (replaces the server-level chat_limit; see assets_limit).
+            limit_req zone=assets_limit burst=400 nodelay;
             expires 1y;
             add_header Cache-Control "public, immutable" always;
         }
@@ -93,6 +103,8 @@ server {
     # Cache content-addressed static assets aggressively
     location ~* \.(?:js|css|woff2?|png|svg|ico|webp)$ {
         include snippets/cinny-security-headers.conf;
+        # Own budget (replaces the server-level chat_limit; see assets_limit).
+        limit_req zone=assets_limit burst=400 nodelay;
         expires 1y;
         add_header Cache-Control "public, immutable" always;
     }
@@ -189,6 +201,8 @@ server {
         }
         location ~* \.(?:js|css|woff2?|png|svg|ico|webp|wasm)$ {
             include snippets/cinny-security-headers-call.conf;
+            # Own budget (replaces the server-level chat_limit; see assets_limit).
+            limit_req zone=assets_limit burst=400 nodelay;
             expires 1y;
             add_header Cache-Control "public, immutable" always;
         }