feat: add reply/forward/pin message flow across backend and web

- add reply_to/forwarded_from message fields and chat pinned_message field

- add forward and pin APIs plus reply support in message create

- wire web actions: Reply, Fwd, Pin and reply composer state

- fix spam policy bug: allow repeated identical messages, keep rate limiting

alembic/versions/0004_reply_forward_pin.py

@@ -0,0 +1,64 @@
+"""reply forward pin
+
+Revision ID: 0004_reply_forward_pin
+Revises: 0003_search_indexes
+Create Date: 2026-03-08 03:20:00.000000
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+
+revision: str = "0004_reply_forward_pin"
+down_revision: Union[str, Sequence[str], None] = "0003_search_indexes"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column("messages", sa.Column("reply_to_message_id", sa.Integer(), nullable=True))
+    op.add_column("messages", sa.Column("forwarded_from_message_id", sa.Integer(), nullable=True))
+    op.create_foreign_key(
+        op.f("fk_messages_reply_to_message_id_messages"),
+        "messages",
+        "messages",
+        ["reply_to_message_id"],
+        ["id"],
+        ondelete="SET NULL",
+    )
+    op.create_foreign_key(
+        op.f("fk_messages_forwarded_from_message_id_messages"),
+        "messages",
+        "messages",
+        ["forwarded_from_message_id"],
+        ["id"],
+        ondelete="SET NULL",
+    )
+    op.create_index(op.f("ix_messages_reply_to_message_id"), "messages", ["reply_to_message_id"], unique=False)
+    op.create_index(op.f("ix_messages_forwarded_from_message_id"), "messages", ["forwarded_from_message_id"], unique=False)
+
+    op.add_column("chats", sa.Column("pinned_message_id", sa.Integer(), nullable=True))
+    op.create_foreign_key(
+        op.f("fk_chats_pinned_message_id_messages"),
+        "chats",
+        "messages",
+        ["pinned_message_id"],
+        ["id"],
+        ondelete="SET NULL",
+    )
+    op.create_index(op.f("ix_chats_pinned_message_id"), "chats", ["pinned_message_id"], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index(op.f("ix_chats_pinned_message_id"), table_name="chats")
+    op.drop_constraint(op.f("fk_chats_pinned_message_id_messages"), "chats", type_="foreignkey")
+    op.drop_column("chats", "pinned_message_id")
+
+    op.drop_index(op.f("ix_messages_forwarded_from_message_id"), table_name="messages")
+    op.drop_index(op.f("ix_messages_reply_to_message_id"), table_name="messages")
+    op.drop_constraint(op.f("fk_messages_forwarded_from_message_id_messages"), "messages", type_="foreignkey")
+    op.drop_constraint(op.f("fk_messages_reply_to_message_id_messages"), "messages", type_="foreignkey")
+    op.drop_column("messages", "forwarded_from_message_id")
+    op.drop_column("messages", "reply_to_message_id")