refactor: rename package fabledassistant -> scribe (code-only)

Renames src/fabledassistant -> src/scribe and all imports, plus the
default DB name and DB user/password (fabled -> scribe) in config +
compose. 952 refs / 154 files. Reverses the old 'internal name stays
fabledassistant' convention.

Code-only: live databases are still physically named 'fabledassistant'.
Deployed environments must set POSTGRES_DB / POSTGRES_USER (or rename the
DB) since the defaults now resolve to 'scribe'. Repo (FabledScribe), git
host (fabledsword), MCP (fabled-git) and the image name (fabledscribe)
are intentionally unchanged.

ruff check src/ clean locally; CI (typecheck + pytest) is the gate.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/views/SettingsView.vue

@@ -510,7 +510,7 @@ async function exportData(scope: "user" | "full") {
     const blob = new Blob([JSON.stringify(data, null, 2)], { type: "application/json" });
     const a = document.createElement("a");
     a.href = URL.createObjectURL(blob);
-    a.download = `fabledassistant-backup-${scope}-${new Date().toISOString().slice(0, 10)}.json`;
+    a.download = `scribe-backup-${scope}-${new Date().toISOString().slice(0, 10)}.json`;
     a.click();
     URL.revokeObjectURL(a.href);
     toastStore.show("Backup downloaded");
@@ -533,7 +533,7 @@ async function exportNotes(format: "markdown" | "json") {
     const stamp = new Date().toISOString().slice(0, 10);
     const a = document.createElement("a");
     a.href = URL.createObjectURL(blob);
-    a.download = `fabledassistant-${stamp}.${ext}`;
+    a.download = `scribe-${stamp}.${ext}`;
     a.click();
     URL.revokeObjectURL(a.href);
     toastStore.show("Export downloaded");