feat: initial shared library extraction

Contains shared infrastructure for all coop services:
- shared/ (factory, urls, user_loader, context, internal_api, jinja_setup)
- models/ (User, Order, Calendar, Ticket, Product, Ghost CMS)
- db/ (SQLAlchemy async session, base)
- suma_browser/app/ (csrf, middleware, errors, authz, redis_cacher, payments, filters, utils)
- suma_browser/templates/ (shared base layouts, macros, error pages)
- static/ (CSS, JS, fonts, images)
- alembic/ (database migrations)
- config/ (app-config.yaml)
- editor/ (Lexical editor Node.js build)
- requirements.txt

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

alembic/versions/0010_add_post_likes.py

@@ -0,0 +1,64 @@
+"""Add post_likes table for liking blog posts
+
+Revision ID: 0010_add_post_likes
+Revises: 0009_add_slot_id_to_entries
+Create Date: 2025-12-07 13:00:00.000000
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = "0010_add_post_likes"
+down_revision = "0009_add_slot_id_to_entries"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "post_likes",
+        sa.Column("id", sa.Integer(), primary_key=True, autoincrement=True),
+        sa.Column(
+            "user_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column(
+            "post_id",
+            sa.Integer(),
+            sa.ForeignKey("posts.id", ondelete="CASCADE"),
+            nullable=False,
+        ),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.text("now()"),
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.text("now()"),
+        ),
+        sa.Column(
+            "deleted_at",
+            sa.DateTime(timezone=True),
+            nullable=True,
+        ),
+    )
+
+    # Index for fast user+post lookups
+    op.create_index(
+        "ix_post_likes_user_post",
+        "post_likes",
+        ["user_id", "post_id"],
+        unique=False,
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("ix_post_likes_user_post", table_name="post_likes")
+    op.drop_table("post_likes")