Give Requests its own colour instead of leaving 4 fastext entries plain

Plain ink for Watch/Requests/Activity/Settings read as flat and
unfinished, not deliberate — user feedback: "the new colors are
awful and basically the same color." Requests gets magenta
(--pending) back: not an arbitrary reuse, it's the same colour a
request already carries once approved elsewhere in the app, and
Requests genuinely is "waiting on a human." That's the real ceiling
though — the locked eight teletext colours leave exactly five legible
as text on black (blue fails contrast, black is invisible on black),
so Watch/Activity/Settings still share plain ink rather than a sixth
colour that doesn't exist in this palette.

app.py

@@ -1304,20 +1304,24 @@ def service_urls():
 
 
 # Every destination, for the top of every page but the index. Order
-# matches nav_items. Colour is semantic everywhere else in this app
-# (red = off-air, magenta = needs a decision, ...), so only the four
-# that still carry a real teletext keyboard shortcut (r/g/y/c) get a
-# colour swatch; the rest render in plain ink rather than borrowing
-# one of the four colours for a destination it doesn't mean.
+# matches nav_items. The locked eight teletext colours leave exactly
+# five that read as text on black without inventing a ninth tone or
+# borrowing a colour that already means something else here: the four
+# with a real keyboard shortcut (r/g/y/c), plus magenta for Requests —
+# not arbitrary, it's the same --pending magenta a request already
+# shows once approved elsewhere, and Requests IS "waiting on a human".
+# Blue fails contrast as text and black is invisible on black, so the
+# three destinations left over (Watch/Activity/Settings) share plain
+# ink rather than a sixth colour that doesn't exist in this palette.
 FULL_FASTEXT = [
-    ("k-red",    "r", "100", "Index",    "/"),
-    ("",         "",  "101", "Watch",    "/watch"),
-    ("k-green",  "g", "102", "Library",  "/library"),
-    ("k-yellow", "y", "103", "Discover", "/discover"),
-    ("",         "",  "104", "Requests", "/requests"),
-    ("k-cyan",   "c", "105", "System",   "/system"),
-    ("",         "",  "106", "Activity", "/activity"),
-    ("",         "",  "900", "Settings", "/settings"),
+    ("k-red",     "r", "100", "Index",    "/"),
+    ("",          "",  "101", "Watch",    "/watch"),
+    ("k-green",   "g", "102", "Library",  "/library"),
+    ("k-yellow",  "y", "103", "Discover", "/discover"),
+    ("k-magenta", "",  "104", "Requests", "/requests"),
+    ("k-cyan",    "c", "105", "System",   "/system"),
+    ("",          "",  "106", "Activity", "/activity"),
+    ("",          "",  "900", "Settings", "/settings"),
 ]
 
 # The index's own closing row: just the four letter keys, since the