feat(dashboard): permission grants count in every dashboard permission check

What someone may do on the dashboard is now their GM level's permissions plus the grants on their account, minus its
denies (PermissionGrants.h). A deny beats a grant; denies never apply to GM 9, and settings and permissions_manage stay
GM 9 only. The account's grants are read with every request (like its GM level), so a change applies at once, and
they are passed through every check: RouteUtils::Can, CanViewCharacter, the rank rules (self_* and manage_equal_rank),
routes guarded by a permission, the templates' `can`, the API documentation, API access, API key scopes (a key never
does more than its owner may now) and WebSocket subscriptions.

New permission grants_manage (GM 9 by default) and the API to manage grants: GET /api/grants/catalog, GET /api/grants,
POST /api/grants, POST /api/grants/:id/remove. Nobody grants or takes away what they don't hold themselves (a
permission, every permission of a group, a command they may use, every command up to their own GM level), and only on
accounts the rank rules let them manage (their own with self_moderation). Commands with a fixed level or a floor
above GM 1 (/execute) can't be granted. Every change goes in the audit log (grant_permission, deny_permission,
remove_grant). Also: the Showcase gate and the traffic subscription now check their permission by name.

Check: grant a GM 2 account accounts_ban (it can ban, and the Ban button shows); deny a GM 8 account accounts_view (the
accounts list is refused); give an expiry a minute ahead and see it stop; try to grant a permission your account
doesn't have (refused); dWebTests PermissionGrantsTests.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dDatabase/GameDatabase/PermissionGrantsLoader.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <ctime>
+#include <memory>
+
+#include "Database.h"
+#include "PermissionGrants.h"
+
+namespace PermissionGrants {
+	// The grants in force now of an account and, when characterId isn't 0, one of its characters (charinfo ID)
+	inline std::shared_ptr<const Held> Load(uint32_t accountId, int64_t characterId = 0) {
+		auto held = std::make_shared<Held>();
+		if (accountId == 0) return held;
+		for (auto& row : Database::Get()->GetActivePermissionGrants(accountId, characterId, static_cast<int64_t>(std::time(nullptr)))) {
+			held->Add(row.kind, std::move(row.name), row.deny, row.expiresAt);
+		}
+		return held;
+	}
+}