feat: Fenris persistent TUI monitoring redesign

Implement the complete redesign per fenris-redesign spec:

- Observation store: SQLite WAL mode, six entities, schema versioning
- Collector: smartctl acquisition, sysfs identity, normalization
- Projection: sustained regime rate, habit change, confidence states
- Panes TUI: Textual keyboard-first layout with four normative regions
- Status CLI: read-only composition with four service facts
- Monitor helper: polkit-guarded toggle, collect, baseline ops
- Legacy migration: idempotent single-transaction import
- Hour classification, day aggregates, monitoring periods
- Pruning, segmentation, drive health facts

Cross-cutting acceptance sweep (CI-1 through CI-4):
- 59 tests covering state matrix, TUI/CLI parity, prohibition set,
  required wording and six disclosures
- Full suite: 289 tests, all green

Issues #20, #32 closed.

scripts/fenris

@@ -94,6 +94,26 @@ def cmd_import(args: argparse.Namespace) -> None:
     print("Legacy import: use fenris-import directly")
 
 
+def cmd_migrate(args: argparse.Namespace) -> None:
+    """Apply forward-only schema migrations (IN-5, IN-6).
+    
+    Called by 'sudo make upgrade'. Raises on newer-schema store.
+    """
+    from fenris.store import migrate_to_latest
+    from pathlib import Path
+
+    store_path = Path("/var/lib/fenris/observations.db")
+    if not store_path.exists():
+        print("No observation store found — nothing to migrate.")
+        return
+
+    steps = migrate_to_latest(store_path)
+    if steps:
+        print(f"Migration complete: {steps} step(s) applied.")
+    else:
+        print("Schema already current.")
+
+
 def main() -> None:
     parser = argparse.ArgumentParser(
         prog="fenris",
@@ -145,6 +165,10 @@ def main() -> None:
     import_parser.add_argument("path", help="Path to history.jsonl")
     import_parser.set_defaults(func=cmd_import)
 
+    # Migrate (IN-5, IN-6) — called by upgrade, not for human use
+    migrate_parser = subparsers.add_parser("migrate", help=argparse.SUPPRESS)
+    migrate_parser.set_defaults(func=cmd_migrate)
+
     # Rejected commands
     for cmd in ["start", "stop", "run"]:
         reject_parser = subparsers.add_parser(cmd, help=argparse.SUPPRESS)
@@ -172,6 +196,8 @@ def main() -> None:
         args.func(args)
     elif args.command == "import":
         cmd_import(args)
+    elif args.command == "migrate":
+        cmd_migrate(args)
 
 
 if __name__ == "__main__":