feat(base,app,learn,todo,train,meditate): agent accounts with tokens

ADR 0044's step 6a (D42, D43, D45): accounts for programs, such as AI
assistants, that an identified person makes from the Profile.

halkyon_base keeps them on the instance's register, which its members
ask: an agent is an account (agent_account: its owner, its name, its
public keys, set by itself once) with one token (agent_token: 32
random bytes, kept as their SHA-256 alone, shown once). agents.create,
mine, newToken, revoke, delete and setKeys serve its owner;
agentSignIn.signIn exchanges the token for an ordinary server-side
session of a day, with the scopes identified and agent, at most 60
sign-ins an hour from a network. Revoking a token or making a new one
ends the agent's sessions; a token unused for 90 days lapses in every
service's pruning. Up to 5 agents a person, where the operator didn't
switch them off (AGENTS=off; said on the privacy page and in
instance.basics). An agent makes no agents, creates or owns no shared
space, is invited and raised as a Viewer alone, is never handed a
space on, is named no operator and granted no assistants; each refusal
has its test. Deleting a person deletes their agents first; an agent's
public profile names whose agent it is.

In the apps, every Profile has an Agents card (halkyon_app's
AgentsSection): made with a name and a handle, its token shown once to
copy, a new token, the token taken back, deleted. Learn's Share sheet
marks an agent among the members and offers it no role above Viewer.

The migrations, the module's and each host's (Learn, Meditate, Todo,
Train), are additive alone: CREATE TABLE "agent_account" with a unique
index on "agentId" (one row an agent account) and one on "ownerId" (a
person's agents, and deleting them with the person), and CREATE TABLE
"agent_token" with unique indexes on "agentId" (one token an agent)
and "tokenHash" (the sign-in finds the token by its hash). No existing
table is touched, so the server before the deploy keeps working on the
migrated database.

Whats-New: Make agents in your Profile: accounts for programs such as AI assistants, which sign in with a token and see only what you share with them.
Whats-New-De: Leg in deinem Profil Agenten an: Konten für Programme wie KI-Assistenten, die sich mit einem Token anmelden und nur sehen, was du mit ihnen teilst.

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/lib/l10n/halkyon_app_localizations_en.dart

@@ -2037,6 +2037,117 @@ class HalkyonAppLocalizationsEn extends HalkyonAppLocalizations {
 
   @override
   String get mobileDataBannerNotNow => 'Not now';
+
+  @override
+  String get agentsTitle => 'Agents';
+
+  @override
+  String get agentsIntro =>
+      'An agent is an account of yours for a program, such as an AI assistant. It signs in with a token, sees only what you invite it to, as a Viewer, and suggests changes rather than making them.';
+
+  @override
+  String get agentsNone => 'No agents yet.';
+
+  @override
+  String get agentsMake => 'Make an agent';
+
+  @override
+  String get agentsName => 'Name';
+
+  @override
+  String get agentsMakeAction => 'Make';
+
+  @override
+  String agentsTokenTitle(String handle) {
+    return 'Token for @$handle';
+  }
+
+  @override
+  String get agentsTokenBody =>
+      'Give this token to the program the agent is for. It\'s shown only now: if it\'s lost, make a new one. Unused for 90 days, it lapses.';
+
+  @override
+  String get agentsTokenCopy => 'Copy token';
+
+  @override
+  String get agentsTokenCopied => 'Token copied';
+
+  @override
+  String get agentsDone => 'Done';
+
+  @override
+  String agentsLastUsed(String handle, String date) {
+    return '@$handle · signed in $date';
+  }
+
+  @override
+  String agentsNeverUsed(String handle) {
+    return '@$handle · never signed in';
+  }
+
+  @override
+  String agentsNoToken(String handle) {
+    return '@$handle · no token';
+  }
+
+  @override
+  String get agentsNewToken => 'New token';
+
+  @override
+  String get agentsRevoke => 'Take back token';
+
+  @override
+  String agentsRevokeTitle(String handle) {
+    return 'Take back @$handle\'s token?';
+  }
+
+  @override
+  String get agentsRevokeMessage =>
+      'It signs in no more, and its sessions end, until you give it a new token.';
+
+  @override
+  String get agentsDelete => 'Delete';
+
+  @override
+  String agentsDeleteTitle(String handle) {
+    return 'Delete @$handle?';
+  }
+
+  @override
+  String get agentsDeleteMessage =>
+      'Its account goes, and with it its memberships.';
+
+  @override
+  String agentsActions(String handle) {
+    return 'Options for @$handle';
+  }
+
+  @override
+  String get agentProblemAgentsOff => 'This instance doesn\'t allow agents.';
+
+  @override
+  String agentProblemTooMany(int count) {
+    return 'You have as many agents as you may ($count).';
+  }
+
+  @override
+  String get agentProblemNameTooLong => 'This name is too long.';
+
+  @override
+  String get agentProblemNotFound => 'This agent is gone.';
+
+  @override
+  String get agentProblemFailed =>
+      'The instance couldn\'t be reached. Try again.';
+
+  @override
+  String agentOf(String owner) {
+    return 'Agent of @$owner';
+  }
+
+  @override
+  String get operatorIsAgent =>
+      'An agent can\'t be an operator or be granted assistants.';
 }
 
 /// The translations for English, as used in the United Kingdom (`en_GB`).