Rollback: revert multi-cohort and all subsequent changes

Reverts commits 7cd390c..c5f4008 (15 commits) to restore the
pre-multi-cohort state. Critical event tomorrow — rolling back to
last known stable state.

Reverted commits:
- 7cd390c Multi-cohort support with per-member initial balance (#358)
- 1a9259e Allow sudoed admins higher decimal precision (#370)
- 612f7e7 Add select all / clear buttons to transfer recipient multiselect (#350)
- ec96705 Link cohort members to existing users when added by email (#378)
- eed7a73 Consolidate admin page data loading into single /api/admin/overview (#381)
- eac92d0 Populate global user display name from id_token on login (ARB-515) (#380)
- c5461ee Remove redundant Refresh button from /admin page (#382)
- 77168e3 Sync Kinde admin role into global_user.is_admin (ARB-512) (#379)
- 685ee0c Remove dead get_market_positions and fix 0.5.0 ImportError (#385)
- e9d49f7 Constrain initial balance inputs to numeric values (#383)
- 95ff300 Stop overwriting global_user display_name on admin REST calls (#386)
- 0163100 Show user email on admin page while editing display name (#387)
- 85f2c5f Fix user selection dropdown hover when multiple users have same name (#388)
- 3fedb38 Add admins to cohort member list on access (ARB-510) (#389)
- c5f4008 Fan out display-name rename to every cohort (ARB-513) (#390)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: briansmiley

.dockerignore

@@ -5,6 +5,4 @@ node_modules
 backend/uploads
 .dev-ports
 .playwright-cli
-.claude/worktrees/
-.vercel
 .claude

.gitignore

@@ -256,7 +256,7 @@ Copy the appropriate template to `frontend/.env` for your use case:
 
 #### `backend/src/main.rs`
 - **Entry point** for the backend server
-- Initializes Axum router with per-cohort WebSocket handler at `/api/ws/:cohort_name`, admin/user REST endpoints, and image upload/serving routes
+- Initializes Axum router with WebSocket handler at `/api`, image upload/serving routes, and Airtable sync endpoint
 - Implements port binding with fallback logic (tries sequential ports if in use)
 - Manages uploads directory and request body size limits
 - Depends on `lib.rs` for `AppState`, `handle_socket.rs` for WebSocket handling
@@ -266,7 +266,7 @@ Copy the appropriate template to `frontend/.env` for your use case:
 - Defines `AppState` struct containing DB connection pool, pub/sub subscriptions, and rate limiters
 - Configures separate admin/user rate limit quotas for expensive queries and mutations
 - Includes protobuf module generation via `build.rs`
-- Declares modules: `websocket_api`, `auth`, `db`, `global_db`, `handle_socket`, `subscriptions`, `convert`, `seed`, `test_utils`
+- Declares modules: `websocket_api`, `auth`, `db`, `handle_socket`, `subscriptions`, `airtable_users`, `convert`, `seed`, `test_utils`
 
 #### `backend/src/handle_socket.rs`
 - Core WebSocket request/response handler (~1150 lines)
@@ -301,6 +301,11 @@ Copy the appropriate template to `frontend/.env` for your use case:
 - Implements `From` trait for all domain types (Portfolio, Market, Order, Trade, Transfer, Account, Auction)
 - Converts Rust Decimal to protobuf floats, timestamps to protobuf Timestamp format
 
+#### `backend/src/airtable_users.rs`
+- Syncs Airtable student records to Kinde and database
+- Creates Kinde accounts and DB entries, assigns initial balances based on product ID
+- Caches Kinde API tokens, logs errors back to Airtable
+
 #### `backend/src/seed.rs`
 - Development seed data (feature-gated behind `dev-mode`)
 - Seeds fresh databases with test accounts (Alice, Bob, Charlie, Admin), markets, orders, and trades

.vercelignore

@@ -3,6 +3,3 @@ target/
 db.sqlite
 db.sqlite-shm
 db.sqlite-wal
-*.sqlite
-*.sqlite-shm
-*.sqlite-wal