release: v0.13.2 — PWA cache fix so mobile gets the v0.13.x modal

Mobile operators were never seeing the inline PDF preview, .TXT
download, or Review form that v0.13.0 added — every feature was
working on desktop browsers but invisible in the PWA.

Root cause: backend/static/sw.js had CACHE_VERSION = 'v1', unchanged
since v0.12.x.  The activate handler deletes any cache not matching
CACHE_VERSION, so without a bump the stale sfm-static-v1 cache (with
the pre-v0.13.0 event-modal.js) stayed authoritative.  cacheFirst
strategy served it forever; mobile users effectively saw the v0.12.x
modal regardless of how many times we rebuilt the image.

Fix:
- CACHE_VERSION bumped to 'v0.13.2' (matches backend/main.py VERSION).
  Comment in sw.js documents the convention: any release touching a
  static asset must bump this string.
- event-modal.js added to the precache list so its lifecycle is
  explicitly tied to the SW version bump (installed fresh on activate
  rather than landing via the cacheFirst-then-cached pattern).

Mobile users get the new modal on next page nav: SW update check
picks up the bumped sw.js, skipWaiting installs it, activate evicts
the v1 caches, controllerchange fires, page reloads, fresh
event-modal.js loads.  Worst case ~1h delay from
registration.update() interval; operators can force-refresh by
closing + reopening the PWA.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/static/sw.js

@@ -1,18 +1,27 @@
 /* Service Worker for Seismo Fleet Manager PWA */
 /* Network-first strategy with cache fallback for real-time data */
 
-const CACHE_VERSION = 'v1';
+// IMPORTANT: bump this on every release that touches a precached or
+// runtime-cached static asset (event-modal.js, mobile.js, style.css,
+// templates served at /, etc.).  The activate handler deletes any cache
+// not matching CACHE_VERSION, so old SW caches get evicted and mobile
+// PWA users actually receive the new bundles instead of being stuck on
+// the pre-bump version.  Convention: keep it in sync with the Terra-View
+// version string in backend/main.py.
+const CACHE_VERSION = 'v0.13.2';
 const STATIC_CACHE = `sfm-static-${CACHE_VERSION}`;
 const DYNAMIC_CACHE = `sfm-dynamic-${CACHE_VERSION}`;
 const DATA_CACHE = `sfm-data-${CACHE_VERSION}`;
 
-// Files to precache (critical app shell)
+// Files to precache (critical app shell).  event-modal.js is included
+// so its cache lifecycle is tied to the SW version bump explicitly.
 const STATIC_FILES = [
   '/',
   '/static/style.css',
   '/static/mobile.css',
   '/static/mobile.js',
   '/static/offline-db.js',
+  '/static/event-modal.js',
   '/static/manifest.json',
   'https://cdn.tailwindcss.com',
   'https://unpkg.com/htmx.org@1.9.10',