Monorepo: consolidate 7 repos into one

Combines shared, blog, market, cart, events, federation, and account
into a single repository. Eliminates submodule sync, sibling model
copying at build time, and per-app CI orchestration.

Changes:
- Remove per-app .git, .gitmodules, .gitea, submodule shared/ dirs
- Remove stale sibling model copies from each app
- Update all 6 Dockerfiles for monorepo build context (root = .)
- Add build directives to docker-compose.yml
- Add single .gitea/workflows/ci.yml with change detection
- Add .dockerignore for monorepo build context
- Create __init__.py for federation and account (cross-app imports)

shared/alembic/versions/p6n4k0l2m3_add_oauth_codes_table.py

@@ -0,0 +1,37 @@
+"""Add oauth_codes table
+
+Revision ID: p6n4k0l2m3
+Revises: o5m3j9k1l2
+Create Date: 2026-02-23
+"""
+from alembic import op
+import sqlalchemy as sa
+
+revision = "p6n4k0l2m3"
+down_revision = "o5m3j9k1l2"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "oauth_codes",
+        sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
+        sa.Column("code", sa.String(128), nullable=False),
+        sa.Column("user_id", sa.Integer(), nullable=False),
+        sa.Column("client_id", sa.String(64), nullable=False),
+        sa.Column("redirect_uri", sa.String(512), nullable=False),
+        sa.Column("expires_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("used_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.PrimaryKeyConstraint("id"),
+        sa.ForeignKeyConstraint(["user_id"], ["users.id"], ondelete="CASCADE"),
+    )
+    op.create_index("ix_oauth_code_code", "oauth_codes", ["code"], unique=True)
+    op.create_index("ix_oauth_code_user", "oauth_codes", ["user_id"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_oauth_code_user", table_name="oauth_codes")
+    op.drop_index("ix_oauth_code_code", table_name="oauth_codes")
+    op.drop_table("oauth_codes")