feat(block1): inventory walking skeleton + first quick-add slice

Stand up the Tanemaki monorepo and the first end-to-end vertical slice of
Block 1 (offline, encrypted inventory): add a seed → see it in a categorized,
searchable list → it persists → reopen and it's still there.

Architecture (state management like G1nkgo, adapted to Tane's reality):
- flutter_bloc (Cubit-first), but the encrypted Drift DB is the single source
  of truth; cubits stream from repositories (no hydrated_bloc/Hive, which would
  write plaintext at rest).
- get_it composition root; go_router; slang i18n (ES/EN, Weblate-friendly JSON).

Workspace & core:
- pub workspace: packages/commons_core (pure Dart) + apps/app_seeds (Flutter).
- commons_core primitives: UUIDv7 IdGen, Hybrid Logical Clock, Quantity value
  type (+ plant-aware QuantityKind), IdentityService root-seed stub.

Data & security:
- Drift schemaVersion=1 with all 10 Block-1 tables + common CRDT columns
  (HLC updated_at, last_author, tombstones); Movement append-only.
- SQLCipher via an injectable executor that refuses to open a plaintext DB;
  DB key + root seed in the OS keystore (separate secrets).
- Exported drift_schema_v1.json + migration scaffold.

Tests (near-TDD; nothing merges without tests):
- commons_core units (24), Drift migration test, "no plaintext at rest"
  security guard (runs where SQLCipher is present, skips otherwise),
  repository, widget, full quick-add flow, file-reopen persistence, and a
  no-hardcoded-strings i18n guard. GitLab CI: format + analyze + test + coverage.

Follow-on Block-1 stories (item detail/edit, species catalog, germination UI)
and all of Block 2 remain out of scope.

apps/app_seeds/lib/security/secret_store.dart

@@ -0,0 +1,27 @@
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+/// Minimal secret key/value store, backed by the OS keystore in production and
+/// trivially fakeable in tests. Keeps [SecureKeyStore] free of plugin calls.
+abstract class SecretStore {
+  Future<String?> read(String key);
+  Future<void> write(String key, String value);
+}
+
+/// OS-keystore-backed implementation (Android Keystore / iOS Keychain / etc.).
+class FlutterSecretStore implements SecretStore {
+  FlutterSecretStore([FlutterSecureStorage? storage])
+    : _storage =
+          storage ??
+          const FlutterSecureStorage(
+            aOptions: AndroidOptions(encryptedSharedPreferences: true),
+          );
+
+  final FlutterSecureStorage _storage;
+
+  @override
+  Future<String?> read(String key) => _storage.read(key: key);
+
+  @override
+  Future<void> write(String key, String value) =>
+      _storage.write(key: key, value: value);
+}