feat: Implement full-stack cohort management with dedicated API, database schema, and admin UI, alongside updates to the database reset script and documentation.

services/lms-service/migrations/20260216000002_cohorts.sql

@@ -0,0 +1,26 @@
+-- Cohorts table
+CREATE TABLE IF NOT EXISTS cohorts (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    organization_id UUID NOT NULL,
+    name TEXT NOT NULL,
+    description TEXT,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    CONSTRAINT cohorts_organization_id_fkey FOREIGN KEY (organization_id) REFERENCES organizations(id) ON DELETE CASCADE
+);
+
+-- User-Cohort relationship table (M:N)
+CREATE TABLE IF NOT EXISTS user_cohorts (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    cohort_id UUID NOT NULL,
+    user_id UUID NOT NULL,
+    assigned_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    CONSTRAINT user_cohorts_cohort_id_fkey FOREIGN KEY (cohort_id) REFERENCES cohorts(id) ON DELETE CASCADE,
+    CONSTRAINT user_cohorts_user_id_fkey FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
+    CONSTRAINT user_cohorts_unique UNIQUE (cohort_id, user_id)
+);
+
+-- Indexes for performance
+CREATE INDEX IF NOT EXISTS idx_cohorts_organization_id ON cohorts(organization_id);
+CREATE INDEX IF NOT EXISTS idx_user_cohorts_cohort_id ON user_cohorts(cohort_id);
+CREATE INDEX IF NOT EXISTS idx_user_cohorts_user_id ON user_cohorts(user_id);