feat: event detail page styling and deleted events indicator

- Fix event detail page for direct navigation by using FastHTML's
  idiomatic htmx parameter instead of manual header check
- Add custom toaster.py with HTML support using NotStr to render
  clickable links in toast messages
- Add hx_preserve to toast container to survive HTMX body swaps
- Add is_deleted column to event_log_by_location table
- Update event_log projection revert() to set is_deleted flag
  instead of deleting rows
- Add strikethrough styling for deleted events in event log

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_projection_event_log.py

@@ -405,19 +405,23 @@ class TestEventLogProjectionRevert:
         event = make_product_collected_event(event_id, location_id, animal_ids)
         projection.apply(event)
 
-        # Verify row exists
-        count = seeded_db.execute("SELECT COUNT(*) FROM event_log_by_location").fetchone()[0]
-        assert count == 1
+        # Verify row exists and is not deleted
+        row = seeded_db.execute(
+            "SELECT is_deleted FROM event_log_by_location WHERE event_id = ?", (event_id,)
+        ).fetchone()
+        assert row[0] == 0
 
         # Revert
         projection.revert(event)
 
-        # Verify row removed
-        count = seeded_db.execute("SELECT COUNT(*) FROM event_log_by_location").fetchone()[0]
-        assert count == 0
+        # Verify row is marked as deleted (not removed)
+        row = seeded_db.execute(
+            "SELECT is_deleted FROM event_log_by_location WHERE event_id = ?", (event_id,)
+        ).fetchone()
+        assert row[0] == 1
 
     def test_revert_only_affects_specific_event(self, seeded_db):
-        """Revert only removes the specific event log entry."""
+        """Revert only marks the specific event log entry as deleted."""
         row = seeded_db.execute("SELECT id FROM locations WHERE name = 'Strip 1'").fetchone()
         location_id = row[0]
 
@@ -439,16 +443,23 @@ class TestEventLogProjectionRevert:
         )
         projection.apply(event2)
 
-        # Verify both exist
+        # Verify both exist and are not deleted
         count = seeded_db.execute("SELECT COUNT(*) FROM event_log_by_location").fetchone()[0]
         assert count == 2
 
         # Revert only event1
         projection.revert(event1)
 
-        # Event2 should still exist
-        count = seeded_db.execute("SELECT COUNT(*) FROM event_log_by_location").fetchone()[0]
-        assert count == 1
+        # Event1 should be marked as deleted
+        row = seeded_db.execute(
+            "SELECT is_deleted FROM event_log_by_location WHERE event_id = ?",
+            ("01ARZ3NDEKTSV4RRFFQ69G5001",),
+        ).fetchone()
+        assert row[0] == 1
 
-        row = seeded_db.execute("SELECT event_id FROM event_log_by_location").fetchone()
-        assert row[0] == "01ARZ3NDEKTSV4RRFFQ69G5002"
+        # Event2 should still be active (not deleted)
+        row = seeded_db.execute(
+            "SELECT is_deleted FROM event_log_by_location WHERE event_id = ?",
+            ("01ARZ3NDEKTSV4RRFFQ69G5002",),
+        ).fetchone()
+        assert row[0] == 0