feat: add account management, email verification, AI fixes, and user guides

- Profile settings, account transfer, delete/leave account flows
- Email verification with JWT tokens and Resend integration
- AI assistant/copilot fixes: markdown rendering, shared RAG helpers,
  token tracking, input refocus, model_validate usage
- User guides hub + detail pages with 13 topic guides
- Sidebar and top bar navigation for guides

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

backend/alembic/versions/040_add_user_profile_fields.py

@@ -0,0 +1,30 @@
+"""Add user profile fields (phone, job_title, timezone, avatar_url, email_verified_at)
+
+Revision ID: 040
+Revises: fb1481317ff6
+Create Date: 2026-03-03
+"""
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers
+revision = "040"
+down_revision = "e2d81e82ea5e"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("users", sa.Column("phone", sa.String(50), nullable=True))
+    op.add_column("users", sa.Column("job_title", sa.String(255), nullable=True))
+    op.add_column("users", sa.Column("timezone", sa.String(100), nullable=False, server_default="UTC"))
+    op.add_column("users", sa.Column("avatar_url", sa.String(500), nullable=True))
+    op.add_column("users", sa.Column("email_verified_at", sa.DateTime(timezone=True), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("users", "email_verified_at")
+    op.drop_column("users", "avatar_url")
+    op.drop_column("users", "timezone")
+    op.drop_column("users", "job_title")
+    op.drop_column("users", "phone")

backend/alembic/versions/041_add_email_verification_tokens.py

@@ -0,0 +1,30 @@
+"""Add email_verification_tokens table
+
+Revision ID: 041
+Revises: 040
+Create Date: 2026-03-03
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+revision = "041"
+down_revision = "040"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "email_verification_tokens",
+        sa.Column("id", postgresql.UUID(as_uuid=True), primary_key=True),
+        sa.Column("token_hash", sa.String(64), unique=True, nullable=False, index=True),
+        sa.Column("user_id", postgresql.UUID(as_uuid=True), sa.ForeignKey("users.id"), nullable=False, index=True),
+        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()),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("email_verification_tokens")

backend/alembic/versions/042_add_pgvector_and_tree_embeddings.py

@@ -18,7 +18,6 @@ depends_on: Union[str, Sequence[str], None] = None
 
 
 def upgrade() -> None:
-    # Enable pgvector extension
     op.execute("CREATE EXTENSION IF NOT EXISTS vector")
 
     op.create_table(
@@ -31,21 +30,17 @@ def upgrade() -> None:
         sa.Column("node_id", sa.String(100), nullable=True),
         sa.Column("chunk_text", sa.Text(), nullable=False),
         sa.Column("embedding_model", sa.String(50), nullable=False, server_default="voyage-3.5"),
-        sa.Column("embedding", sa.Column.__class__, nullable=True),  # placeholder, replaced below
         sa.Column("meta", postgresql.JSONB(), nullable=False, server_default=sa.text("'{}'::jsonb")),
         sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.text("now()")),
         sa.Column("updated_at", sa.DateTime(timezone=True), server_default=sa.text("now()")),
     )
 
-    # Drop the placeholder embedding column and add the vector column
-    op.drop_column("tree_embeddings", "embedding")
     op.execute("ALTER TABLE tree_embeddings ADD COLUMN embedding vector(1024)")
 
-    # Indexes
     op.create_index("ix_tree_embeddings_account_id", "tree_embeddings", ["account_id"])
     op.create_index("ix_tree_embeddings_tree_id", "tree_embeddings", ["tree_id"])
 
 
 def downgrade() -> None:
     op.drop_table("tree_embeddings")
-    op.execute("DROP EXTENSION IF EXISTS vector")
+    op.execute("DROP EXTENSION IF EXISTS vector")