Add tasks: the crew's shared to-do list

Bots and workspaces each keep a list of work tracked until it's done, and
the bots move it along themselves as they work.

- tasks (one collection per bot or per workspace), task_notes (the
  progress log) and task_media (a deliverable or a reference file, its
  bytes a private media row served at /media/private/<id>)
- statuses todo/doing/blocked/done/cancelled, with blocked_reason while
  only the user can unblock it
- visibility as SQL in src/utils/task-access: a user's own bots and
  workspaces, a run's own list plus its workspaces, everything for the
  coordinator; every tool and endpoint resolves through it
- list_tasks, create_task and update_task on every run, so a chat reply,
  a task and a routine all read the list, log progress and file what they
  produced
- TasksNote on every run and TaskReminderNote in chat, so a greeting or a
  proposed next step brings pending work up in one measured line
- tasks group on the workspace dashboard and a tasks modal in the
  conversation header, sharing one form, row and detail panel
- a bot's or workspace's own chat uploads are read before the delete so
  none are stranded; bot files keep their folder

Also corrects the README's RAM guidance and table alignment.

src/functions/backend/db/tasks/task-scope-values.ts

@@ -0,0 +1,27 @@
+import AppError from "@/src/utils/app-error";
+
+type Params = {
+    bot_id?: number | string | null;
+    workspace_id?: number | string | null;
+};
+
+/**
+ * A task belongs to exactly one collection: a bot's own list, or a
+ * workspace's shared one. Checked in the helpers rather than the schema,
+ * since SQLite treats NULL in a unique constraint as always distinct (the
+ * `envs` precedent).
+ */
+export default function taskScopeValues({ bot_id, workspace_id }: Params) {
+    const bot = bot_id ? Number(bot_id) : null;
+    const workspace = workspace_id ? Number(workspace_id) : null;
+
+    if (bot && workspace) {
+        throw new AppError(`A task belongs to a bot or a workspace, not both.`);
+    }
+
+    if (!bot && !workspace) {
+        throw new AppError(`Say which bot or workspace the task is for.`);
+    }
+
+    return { bot_id: bot, workspace_id: workspace };
+}