fix(dev): idempotent Alembic chain for squashed 0001 + clearer dev scripts

- Make migrations 0002–0008 skip schema changes already applied when
  0001_initial creates current ORM (rename segments column, timeline FK,
  memoir phase flags, drop content_tsv, eval_* tables).
- development.sh / internal-eval.sh: surface Alembic stderr, warn on
  docker-style DB hosts, TCP port checks without lsof, verify Uvicorn
  listens before claiming started.

api/alembic/versions/0007_drop_chunk_content_tsv.py

@@ -17,12 +17,22 @@ branch_labels: Union[str, Sequence[str], None] = None
 depends_on: Union[str, Sequence[str], None] = None
 
 
+def _column_names(table_name: str) -> set[str]:
+    bind = op.get_bind()
+    inspector = sa.inspect(bind)
+    return {column["name"] for column in inspector.get_columns(table_name)}
+
+
 def upgrade() -> None:
-    op.drop_column("memory_chunks", "content_tsv")
+    columns = _column_names("memory_chunks")
+    if "content_tsv" in columns:
+        op.drop_column("memory_chunks", "content_tsv")
 
 
 def downgrade() -> None:
-    op.add_column(
-        "memory_chunks",
-        sa.Column("content_tsv", postgresql.TSVECTOR(), nullable=True),
-    )
+    columns = _column_names("memory_chunks")
+    if "content_tsv" not in columns:
+        op.add_column(
+            "memory_chunks",
+            sa.Column("content_tsv", postgresql.TSVECTOR(), nullable=True),
+        )