feat: implement CSS cache-busting for web assets

Amolith and Crush created

Add version query parameters to CSS URLs to force browsers to fetch
newer versions after edits. This ensures users see updated styles
without manually clearing browser cache.

Changes:
- Add ?v=1 to overrides.css and syntax.css URLs
- Document version increment process in AGENTS.md

Implements: bug-9b0a200
Co-Authored-By: Crush <crush@charm.land>

Change summary

AGENTS.md                   | 6 ++++++
pkg/web/templates/base.html | 4 ++--
2 files changed, 8 insertions(+), 2 deletions(-)

Detailed changes

AGENTS.md 🔗

@@ -88,6 +88,12 @@ SOFT_SERVE_DISABLE_RACE_CHECKS=1 go test ./...
 go build -o soft ./cmd/soft
 ```
 
+#### CSS Cache-Busting
+
+When editing CSS files in `pkg/web/static/`, increment the version query parameter in `pkg/web/templates/base.html`:
+- `overrides.css?v=1` → `overrides.css?v=2`
+- `syntax.css?v=1` → `syntax.css?v=2`
+
 ### Environment Variables
 
 All configuration can be set via environment variables with the `SOFT_SERVE_` prefix:

pkg/web/templates/base.html 🔗

@@ -9,8 +9,8 @@
   {{if .Repo}}{{if .Repo.Description}}<meta name="description" content="{{.Repo.Description}}">{{end}}{{end}}
   <link rel="icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🍦</text></svg>">
   <link rel="stylesheet" href="/static/pico-2.1.1-pink.min.css">
-  <link rel="stylesheet" href="/static/overrides.css">
-  <link rel="stylesheet" href="/static/syntax.css">
+  <link rel="stylesheet" href="/static/overrides.css?v=1">
+  <link rel="stylesheet" href="/static/syntax.css?v=1">
 </head>
 <body class="container">
   <a href="#main-content" class="skip-link">Skip to main content</a>