Move dashboard settings into Y3R C4LL tab, drop standalone S3TT1NGS page

mara (issue #3817): remove the home link + page, put the setting toggle into the Y3R C4LL tab. Deleted settings.html/.js/.css; the browser-notification toggle (the only content there) now renders as a ◆ PR3F3R3NC3S ◆ section under Y3R C4LL's approvals/inbox, wired the same way (NOTIF.bind()/NOTIF.show() in common.js — no behavior change, just a new mount point). Updated build.mjs's entry lists and every doc/comment that pointed at the old page.

frontend/packages/shared/src/prefs.ts

@@ -1,10 +1,9 @@
-// Tiny browser-local (localStorage) preference helpers shared by the
-// dashboard's /settings.html and the per-agent page — both need the
-// exact same key name to actually talk to each other via the browser's
-// shared per-origin storage (settings.html is where the operator sets
-// the preference; every per-agent page's terminal reads it), so the
-// get/set pair — and the key itself — live here once rather than as
-// independent copies in each package that could drift out of sync.
+// Tiny browser-local (localStorage) preference helper, in `@hive/shared`
+// so a future second consumer (e.g. swarm-ui's own terminal) gets the
+// exact same key name for free via the browser's shared per-origin
+// storage, rather than an independent copy that could drift.
+// `ExpandDetailsSetting` (the per-agent page's own settings popover) is
+// the only writer today; `Row.tsx` is the only reader.
 
 const EXPAND_DETAILS_KEY = 'hive-agent-expand-details';