Give Activity a genuine ninth colour: --tt-orange

Requested directly: "can we make activity orange". The locked eight
palette had already run out at six legible text colours (Watch's blue
was the last one, and it's already a contrast exception); a dithered
swatch alone read as unfinished, and dithering the word itself
rendered as illegible static — tried and reverted this session.

--tt-orange (#ff8000) is defined in base.css right after the locked
eight, clearly marked as a deliberate, acknowledged one-off exception
to "eight colours, no ninth" rather than a secretly-smuggled-in tint.
Same flat text+swatch treatment as every other fastext key. Updated
CLAUDE.md's discipline 1 and DESIGN.md's Locked Eight Rule to name the
exception explicitly, so it reads as a documented decision next time
someone audits the palette, not a bug.

app.py

@@ -1304,20 +1304,22 @@ def service_urls():
 
 
 # Every destination, for the top of every page but the index, each
-# with its own distinct treatment. Order matches nav_items. Six of the
-# eight get a flat colour, text and swatch both: the four with a real
-# keyboard shortcut (r/g/y/c), plus magenta for Requests (the same
-# --pending magenta a request already shows once approved elsewhere —
-# Requests IS "waiting on a human") and blue for Watch. Blue is ~2.4:1
-# contrast on black, well under the 4.5:1 every other body text here
-# clears — a known, deliberate exception, not an oversight; it's set
-# this way because coloured-icon-only for Watch read as unfinished
-# next to six fully-coloured neighbours. Activity gets an ordered
-# dither swatch instead of a flat colour, the one other legal way to
-# get a distinct mark out of this palette without smuggling in a ninth
-# hue. Settings alone keeps plain ink — deliberately, as the one page
-# with no live status of its own, so it's the one that gets no colour
-# rather than an arbitrary leftover.
+# with its own distinct colour. Order matches nav_items. The four
+# with a real keyboard shortcut (r/g/y/c) keep their original colours;
+# Requests gets magenta (the same --pending magenta a request already
+# shows once approved elsewhere — Requests IS "waiting on a human");
+# Watch gets blue, ~2.4:1 contrast on black versus the 4.5:1 every
+# other body text here clears — a known, deliberate exception, kept
+# anyway because a swatch-only accent read as unfinished next to six
+# fully-coloured neighbours. That's every colour the locked eight
+# palette has to give (black's invisible on black); Activity's colour,
+# --tt-orange, is a genuine ninth on top of it — a dithered swatch
+# alone read as unfinished, and dithering the word itself renders
+# illegible, so it's a deliberate, acknowledged break from "eight
+# colours, no ninth" rather than a fix that stays inside it. Settings
+# alone keeps plain ink — deliberately, as the one page with no live
+# status of its own, so it's the one that gets no colour rather than
+# an arbitrary leftover.
 FULL_FASTEXT = [
     ("k-red",     "r", "100", "Index",    "/"),
     ("k-blue",    "",  "101", "Watch",    "/watch"),
@@ -1325,7 +1327,7 @@ FULL_FASTEXT = [
     ("k-yellow",  "y", "103", "Discover", "/discover"),
     ("k-magenta", "",  "104", "Requests", "/requests"),
     ("k-cyan",    "c", "105", "System",   "/system"),
-    ("k-dither",  "",  "106", "Activity", "/activity"),
+    ("k-orange",  "",  "106", "Activity", "/activity"),
     ("",          "",  "900", "Settings", "/settings"),
 ]