feat(theme): repoint unthrown to teal, retire demesne and start

Red is stop and green is all-clear. A modelled error is neither — unthrown's
whole claim is that a failure is not an emergency but an anticipated case,
typed in E and matched exhaustively. So the accent moves outside the signal
register entirely: not a signal, a value.

#46B86C was also byte-identical to --bt-green, the org's checkmark ink, so
unthrown was the one package whose "own" accent was org chrome — the thing the
multi-accent rule forbids. --bt-green / --green / --text-green are untouched
and now uncontested.

The logo's no-throw sign (circle + slash) moves with it: #3FB0A5 on dark,
#2F847C on light, keeping the pair's existing 0.75 ratio. Both clear the 3:1
non-text contrast threshold, and the light variant improves on the old green
(4.24 vs 4.08 on #FAF9FA).

demesne and start no longer exist, so their tokens, design.md rows and logo
assets go with them. CHANGELOG.md and .hallmark/log.json still name them, as
history should.

Author: btravers

.changeset/teal-unthrown-accent.md

@@ -0,0 +1,13 @@
+---
+"@btravstack/theme": minor
+---
+
+Repoint `--pkg-unthrown` to teal `#3FB0A5`, and drop the retired `--pkg-demesne`
+and `--pkg-start` tokens.
+
+Red is stop and green is all-clear; a modelled error is neither, so unthrown's
+accent now sits outside the signal register — not a signal, a value. The old
+`#46B86C` was also byte-identical to `--bt-green`, the org's checkmark ink, so
+unthrown was the one package whose accent was org chrome.
+
+`--bt-green` / `--green` / `--text-green` are unchanged.

apps/website/public/logos/demesne-dark.svg

@@ -9,7 +9,7 @@ grow.
 *colorful stack of distinct tools* on a near-neutral black canvas: the
 beetroot pink is the ORG accent (wordmark, links, CTAs, mascot), while each
 package glows in **its own accent** — amqp orange, temporal indigo, unthrown
-green, demesne violet. Weight-contrast typography (one grotesque at 400 vs
+teal. Weight-contrast typography (one grotesque at 400 vs
 800), elevation through surface lightness, real numbers in the hero, and the
 gradient beetroot mascot as the one character moment.
 
@@ -54,9 +54,7 @@ atmospheric (studied register — dark, quiet, confident; no blooms).
 | `--accent` (org) | **#E0589A** — THE knob | same (text darkens for AA) |
 | `--pkg-amqp` | `#FF6600` | darken 30% at point of use |
 | `--pkg-temporal` | `#6B76F2` | darken 30% at point of use |
-| `--pkg-unthrown` | `#46B86C` | darken 30% at point of use |
-| `--pkg-demesne` | `#B45CE0` | darken 30% at point of use |
-| `--pkg-start` | `#22B8CF` | darken 30% at point of use |
+| `--pkg-unthrown` | `#3FB0A5` | darken 30% at point of use |
 
 **The multi-accent rule (the studied signature).** The canvas and chrome are
 near-neutral; color belongs to the *products*. Package names, category dots
@@ -150,9 +148,7 @@ The canonical export lives at `packages/theme/src/tokens.css` (published as
   --color-accent:  #E0589A;            /* org */
   --pkg-amqp:      #FF6600;
   --pkg-temporal:  #6B76F2;
-  --pkg-unthrown:  #46B86C;
-  --pkg-demesne:   #B45CE0;
-  --pkg-start:     #22B8CF;
+  --pkg-unthrown:  #3FB0A5;
   --font-display:  "Geist", sans-serif; /* 800 for display */
   --font-body:     "Geist", sans-serif;
   --font-mono:     "JetBrains Mono", monospace;

apps/website/public/logos/demesne-light.svg

@@ -14,7 +14,7 @@
  * glows in ITS OWN accent — the org reads as a colorful stack of distinct
  * tools, not a monochrome brand. The beetroot pink is the ORG accent
  * (wordmark, links, org CTAs); the per-package accents (amqp orange,
- * temporal indigo, unthrown green, demesne violet) carry the packages.
+ * temporal indigo, unthrown teal) carry the packages.
  * Elevation through lightness, weight-contrast typography, real numbers.
  *
  * DARK is the canonical default. The light scheme overrides the semantic
@@ -40,11 +40,9 @@
 
   /* The stack — official per-package accents (docs sites set these as
      their own --accent; the landing shows them side by side). */
-  --pkg-amqp:     #FF6600;
-  --pkg-temporal: #6B76F2;
-  --pkg-unthrown: #46B86C;
-  --pkg-demesne:  #B45CE0;
-  --pkg-start:    #22B8CF;
+  --pkg-amqp:     #FF6600;   /* RabbitMQ's orange */
+  --pkg-temporal: #6B76F2;   /* Temporal's indigo */
+  --pkg-unthrown: #3FB0A5;   /* outside the signal register: not a signal, a value */
 
   /* ── Surfaces (DARK scheme — canonical: near-neutral black) ──── */
   --bg:        oklch(13% 0.006 310);   /* ≈ #080709 — the canvas */