feat(web/panettone): Support full-text search of issues

Support basic full text search of issues using postgresql's built-in
text search. There's a new column on the issues table called `tsv`,
which contains a tsvector of the title concatenated with the
description, and a new search form on both the index and closed issues
page which allows searching that tsvector with a user-supplied query.
Results are ranked according to that text query in the case of a search.

This works fine for now, but next up I'd also like to highlight the
results according to the bits that matched the user's query.

Change-Id: I25170bedbbbcdc3ed29a047962e9fcfe280d763a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11258
Autosubmit: aspen <root@gws.fyi>
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>

web/panettone/src/css.lisp

@@ -49,7 +49,24 @@
        :color "var(--primary)")))
 
     (.comment-count
-     :color "var(--gray)")))
+     :color "var(--gray)")
+
+    (.issue-links
+     :display "flex"
+     :flex-direction "row"
+     :align-items "center"
+     :justify-content "space-between"
+     :flex-wrap "wrap")
+
+    (.issue-search
+     ((:and input (:= type "search"))
+      :padding "0.5rem"
+      :background-image "url('static/search.png')"
+      :background-position "10px 10px"
+      :background-repeat "no-repeat"
+      :background-size "1rem"
+      :padding-left "2rem"
+      :border "1px" "solid" "var(--gray)"))))
 
 (defparameter issue-history-styles
   `((.issue-history
@@ -220,4 +237,15 @@
      :margin "0 auto")
 
     (.created-by-at
-     :color "var(--gray)")))
+     :color "var(--gray)")
+
+    ;; screen-reader-only content
+    (.sr-only
+     :border 0
+     :clip "rect(0 0 0 0)"
+     :height "1px"
+     :margin "-1px"
+     :overflow "hidden"
+     :padding 0
+     :position "absolute"
+     :width "1px")))