Let a bot take any colour

A bot's identity was one of seven hues, and the hue picked both its colour
and its stone shape. Now its colour is free and its stone is its own:

- `bots.color` holds any `#rrggbb`, `bots.stone` the flat-cut shape it's
  drawn on. `bots.hue` stays as the palette column they replaced, read only
  as a fallback; `src/scripts/move-bot-colour-to-owners.ts` backfills an
  install from it (safe to rerun).
- `src/utils/bot-color.ts` is the only place a colour is validated or
  resolved (`resolveBotColor`/`resolveBotStone` carry the old hue forward,
  `botColorNeedsPaperFace` flips the eyes to paper on a very dark body), and
  `src/utils/bot-stone-props.ts` gives every row its props, so a row saved
  before this still renders as it did.
- `BotStone` takes the colour as the body's SVG `fill`, the one documented
  exception to the token rule: an arbitrary hex has no token to point at.
  `UnreadDot` follows it.
- The picker keeps the palette tiles (still shape and colour together) and
  adds a native swatch and a hex field, so a custom colour keeps its stone.
  Same place as before: the header avatar's modal and Settings > Bots, for
  crew managers. The coordinator stays hue-less.
- A recolour reaches other open tabs through `pushBotUpdated`.

src/hooks/use-live-bots.ts

@@ -1,5 +1,5 @@
 import { useState } from "react";
-import type { BUN_SQLITE_COBBLE_BOT_MESSAGES } from "@/db/types/db";
+import type { BUN_SQLITE_COBBLE_BOT_MESSAGES, BUN_SQLITE_COBBLE_BOTS } from "@/db/types/db";
 import type {
     BotCreatedData,
     BotRemovedData,
@@ -78,7 +78,19 @@ export default function useLiveBots({ bots, open_bot_id, workspace_id = null }:
 
                 return prev.map((bot) =>
                     bot.id == data.id
-                        ? { ...bot, face: data.face, status_line: data.status_line }
+                        ? {
+                              ...bot,
+                              face: data.face,
+                              status_line: data.status_line,
+                              ...(data.color !== undefined
+                                  ? { color: data.color || undefined }
+                                  : {}),
+                              ...(data.stone !== undefined
+                                  ? {
+                                        stone: (data.stone || "") as BUN_SQLITE_COBBLE_BOTS["stone"],
+                                    }
+                                  : {}),
+                          }
                         : bot,
                 );
             }),