feat(db): permission_grants, permissions and commands given to one account or character

A new table, permission_grants (MySQL migration 96, SQLite 79), and the IPermissionGrants interface with MySQL, SQLite
and TestSQL implementations. A row grants (or with deny, takes away) a dashboard permission, a slash command, a
permission category or every command up to a GM level, for one account or one character, with an optional expiry, who
granted it and when, and a note. Rows are never deleted: removing one sets revoked_at/revoked_by, so the table is also
the history. Nothing reads it yet.

Check: both migrations run on a fresh and an existing database; DatabaseParityTests PermissionGrants passes against
MariaDB (DLU_TEST_MYSQL_HOST) and SQLite gives the same results.

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

migrations/dlu/sqlite/79_permission_grants.sql

@@ -0,0 +1,17 @@
+/* Permissions and slash commands granted to or taken from one account or character. See the MySQL migration. */
+CREATE TABLE IF NOT EXISTS permission_grants (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    target_type TEXT NOT NULL,
+    target_id BIGINT NOT NULL,
+    kind TEXT NOT NULL,
+    name TEXT NOT NULL,
+    deny INTEGER NOT NULL DEFAULT 0,
+    expires_at BIGINT NOT NULL DEFAULT 0,
+    note TEXT NOT NULL DEFAULT '',
+    granted_at BIGINT NOT NULL,
+    granted_by_id INTEGER NOT NULL DEFAULT 0,
+    granted_by TEXT NOT NULL DEFAULT '',
+    revoked_at BIGINT NOT NULL DEFAULT 0,
+    revoked_by TEXT NOT NULL DEFAULT ''
+);
+CREATE INDEX IF NOT EXISTS permission_grants_target ON permission_grants (target_type, target_id);