Support selectable demo exchanges and configurable analysis limits

Persist manual requests until exchange confirmation, preserve stop protection, and reconcile fills before settling plans. Tighten model stream, crawler, skill, research accounting, and frontend race handling, with regression coverage. Keep queued analyses pending until a fresh account snapshot is available.

backend/alembic/versions/20261020_d2a4c6e8f103_daily_analysis_limit.py

@@ -0,0 +1,21 @@
+"""每日分析上限改为用户配置。
+
+Revision ID: d2a4c6e8f103
+Revises: b8d1f4a92c60
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+revision = "d2a4c6e8f103"
+down_revision = "b8d1f4a92c60"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("trading_account", sa.Column("daily_analysis_limit", sa.Integer(), nullable=False, server_default="60"))
+
+
+def downgrade() -> None:
+    op.drop_column("trading_account", "daily_analysis_limit")