feat(app): the operator's overview of screens, grants to several people at once with one budget each, assistants by provider

Halkyon Learn's ADR 0021, D57 to D63, on halkyon_base's budgets and
effort:

- The operator's screen is an overview (Waiting, Operators, Accounts,
  Assistants, each with its count) whose rows open screens of their own,
  read 50 at a time as they scroll (OperatorListCubit, OperatorPage), so
  hundreds of accounts push nothing else down (D62).
- A handle is picked among the accounts there are (AccountSuggestionField):
  appointing an operator and granting take no other (D61).
- AssistantGrantsScreen replaces AssistantGrantsCard: the assistants set
  up by provider, with their efforts and prices; the people granted, found
  by their handle's start; one sheet granting several assistants, a
  provider's at once, to several people, each with one budget in money and
  tokens a day and a month, or changing one person's (D58, D59).
- Assistants are grouped by provider wherever they are listed, each under
  its name with a dot in its colour (ProviderLabel, D60).
- AssistantsCard shows what is left of the person's budget for all their
  assistants together; the months of the figures run oldest first (D57).
- AssistantChoice says the efforts a question may ask at and the ceiling
  on output each asks for (D63); a person's own key gets none and keeps
  4,096 tokens.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

packages/halkyon_app/README.md

@@ -62,26 +62,40 @@ Written as the apps are: Dart 3.13's primary constructors, Material from
   the person's app opens, after each change, and every 5 minutes only while
   they operate it), `InstanceOperatorCard` or `InstanceOperatorTiles` for an
   app's settings and `WaitingAccountsBadge` for its Settings cog, both
-  nothing at all for anyone else, and `InstanceOperatorScreen`: the accounts
-  that wait, approved once their person confirmed the words read out, or
-  refused; who operates, named by handle and taken back (never the last);
-  accounts found by the start of their handle, suspended or named. Only the
-  register's service answers: on a member, nothing shows.
+  nothing at all for anyone else, and `InstanceOperatorScreen` (D62): an
+  overview of how many wait, operate and have accounts, and of the
+  assistants set up, each row opening a screen of its own, every list read
+  50 at a time as it is scrolled (`OperatorListCubit`, `OperatorPage`): the
+  accounts that wait, approved once their person confirmed the words read
+  out, or refused; who operates, named by a handle picked among those
+  suggested and taken back (never the last); accounts found by the start of
+  their handle, suspended, named or granted assistants. A handle is only
+  ever picked among the accounts there are (`AccountSuggestionField`, D61).
+  Only the register's service answers: on a member, nothing shows.
 - **Assistants** (`lib/src/assistant/`, Halkyon Learn's ADR 0021, step 2):
   `AssistantRepository` on `ServerpodAssistantGateway` (the module's
   `assistant` endpoint; refusals as `AssistantFailed`) asks an
   `AssistantChoice` in halkyon_llm's terms: a `GrantedAssistant` through the
-  instance, which counts it, or a `PersonalAssistant` with the person's own
-  key directly (`LlmClient`), the instance seeing neither key nor question;
+  instance, which counts it, at an effort among those the operator allows
+  and with that effort's ceiling on output (`efforts`, `outputCeilingAt`,
+  D63), or a `PersonalAssistant` with the person's own key directly
+  (`LlmClient`), without an effort and at 4,096 output tokens, the instance
+  seeing neither key nor question;
   `assistant_messages.dart` turns a conversation into the endpoint's models
   and back, part by part. `AssistantsCard` is an app's settings' card: what
-  is granted and left of its limits, agreed to once (the consent sheet),
-  the person's use by UTC month, the instance's privacy page, and the
+  is granted, under each provider's name in its colour (`ProviderLabel`,
+  `providerColorIn`, D60), what is left of the person's budget for them
+  together (D58), each agreed to once (the consent sheet), the person's use
+  by UTC month, oldest first (D57), the instance's privacy page, and the
   person's own assistants where the operator allows them, kept where the
   app says (`OwnAssistantStore`: Learn's sealed settings). For the operator,
-  `AssistantOperatorRepository` (grants by exact handle) and
-  `AssistantGrantsCard` on `InstanceOperatorScreen`: grants with their
-  limits, granted, changed and taken back, and everyone's use by month.
+  `AssistantOperatorRepository` and `AssistantGrantsScreen`, opened from
+  `InstanceOperatorScreen`: the assistants set up, by provider, with their
+  efforts and whether they are priced; the people granted some, each with
+  one budget in money and tokens, a day and a month (D58, D59), found by
+  their handle's start; one sheet granting several assistants, a
+  provider's at once, to several people at once, or changing one person's
+  (`showAssistantGrantSheet`); and everyone's use by month.
   `package:halkyon_app/assistant_models.dart` holds the models alone, in
   pure Dart, for an app's own models. For the app's warnings before a
   private studyset's content goes (ADR 0021, D9): `providerTermsOf` names a