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/functions/backend/db/tasks/grab-task.ts

@@ -25,7 +25,7 @@ export default async function grabTask({ user_id, task_id }: Params): Promise<Ta
     const face = botFaceSql({ user_id, alias: "b", prefix: "bot_" });
 
     const row_res = await BunSQLite.sql<TaskDetail>({
-        sql: `SELECT t.*, b.name AS bot_name, b.kind AS bot_kind, b.hue AS bot_hue,
+        sql: `SELECT t.*, b.name AS bot_name, b.kind AS bot_kind, b.hue AS bot_hue, b.color AS bot_color, b.stone AS bot_stone,
                 b.image_media_id AS bot_image_media_id, ${face.sql}, w.name AS workspace_name
             FROM tasks t
             LEFT JOIN bots b ON b.id = t.bot_id

src/functions/backend/db/tasks/grab-tasks.ts

@@ -83,7 +83,7 @@ export default async function grabTasks({
     const face = botFaceSql({ user_id: user_id || 0, alias: "b", prefix: "bot_" });
 
     const res = await BunSQLite.sql<TaskWithNames>({
-        sql: `SELECT t.*, b.name AS bot_name, b.kind AS bot_kind, b.hue AS bot_hue,
+        sql: `SELECT t.*, b.name AS bot_name, b.kind AS bot_kind, b.hue AS bot_hue, b.color AS bot_color, b.stone AS bot_stone,
                 b.image_media_id AS bot_image_media_id, ${face.sql}, w.name AS workspace_name,
                 (SELECT n.text FROM task_notes n WHERE n.task_id = t.id ORDER BY n.id DESC LIMIT 1) AS latest_note,
                 (SELECT COUNT(*) FROM task_media tm WHERE tm.task_id = t.id) AS media_count