feat: add database schema migrations and seed data

8 SQL migration files covering all 10 tables, RLS policies with
SECURITY DEFINER helpers, and seed data for SCW1 site + 3 zones.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AWxyMibCuGGtSQSqfajDQ7

supabase/migrations/20260709000005_capa_dosh.sql

@@ -0,0 +1,43 @@
+-- supabase/migrations/20260709000005_capa_dosh.sql
+CREATE TYPE capa_priority AS ENUM ('low', 'med', 'high');
+
+CREATE TYPE capa_status AS ENUM (
+  'open', 'in_progress', 'overdue', 'pending_verification',
+  'verified', 'reopened', 'closed'
+);
+
+CREATE TABLE capa_actions (
+  id                       UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  incident_id              UUID NOT NULL REFERENCES incidents(id) ON DELETE RESTRICT,
+  root_cause_ref           TEXT,
+  description              TEXT NOT NULL,
+  owner_user_id            UUID NOT NULL REFERENCES users(id),
+  department               TEXT NOT NULL,
+  due_date                 DATE NOT NULL,
+  priority                 capa_priority NOT NULL DEFAULT 'med',
+  status                   capa_status NOT NULL DEFAULT 'open',
+  completed_at             TIMESTAMPTZ,
+  verified_by              UUID REFERENCES users(id),
+  verified_at              TIMESTAMPTZ,
+  effectiveness_recheck_date DATE,
+  created_at               TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE TYPE dosh_form_type AS ENUM ('jkkp6', 'jkkp7', 'jkkp8');
+CREATE TYPE dosh_status    AS ENUM ('not_required', 'pending', 'submitted');
+
+CREATE TABLE dosh_reports (
+  id           UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  incident_id  UUID NOT NULL REFERENCES incidents(id) ON DELETE RESTRICT,
+  form_type    dosh_form_type NOT NULL,
+  status       dosh_status NOT NULL DEFAULT 'not_required',
+  submitted_at TIMESTAMPTZ,
+  submitted_by UUID REFERENCES users(id),
+  file_url     TEXT,
+  created_at   TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE INDEX capa_actions_incident_idx  ON capa_actions(incident_id);
+CREATE INDEX capa_actions_owner_idx     ON capa_actions(owner_user_id);
+CREATE INDEX capa_actions_status_idx    ON capa_actions(status);
+CREATE INDEX capa_actions_due_date_idx  ON capa_actions(due_date);