Soft-delete + source-count diagnostics; thesis v4 (0.1.0:47)

- DELETE handlers soft-delete (set deleted_at) + cascade contact -> opps/comms/lp
  instead of hard-deleting (guardrail #3); list queries filter deleted rows.
- ingest: chunking excludes soft-deleted records; qdrant delete-by-source-id;
  sync prunes soft-deleted records' vectors incrementally.
- /api/system/status returns raw source-record counts for sanity-checking.
- docs/thesis-seed-v4.md (no "bet" language, scarcity-forward, freedom-tech as
  a banner option, tightened pillars, reworked segments + edge).

Soft-delete verified via the running HTTP server (delete -> hidden + row kept).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/ingest/sync.py

@@ -60,6 +60,18 @@ def _state_set(conn, key, value):
                  (key, value, _now()))
 
 
+def _deleted_source_ids(conn, since):
+    """CRM records soft-deleted since the watermark — their chunks get pruned."""
+    ids = set()
+    for tbl in ("contacts", "organizations", "opportunities", "communications", "lp_profiles"):
+        try:
+            for r in conn.execute(f"SELECT id FROM {tbl} WHERE deleted_at IS NOT NULL AND deleted_at > ?", (since,)):
+                ids.add(r["id"])
+        except Exception:
+            pass
+    return ids
+
+
 def _changed_source_ids(conn, since):
     changed = set()
     for tbl, model in _CHANGE_TABLES:
@@ -91,6 +103,10 @@ def run(db, recreate=False, fuzzy=False, batch=32):
     if last is None or recreate:
         mode, target = "full", all_chunks
     else:
+        # Prune chunks of records soft-deleted since the last sync.
+        deleted = _deleted_source_ids(conn, last)
+        if deleted:
+            qdrant_io.delete_by_source_ids(deleted)
         changed = _changed_source_ids(conn, last)
         mode, target = "incremental", [c for c in all_chunks
                                        if (c["source_model"], c["source_id"]) in changed]