Add API Q1 CAPA: root cause, corrective action gate, effectiveness verification

Implements tester feedback against API Q1 §5.9.1.2 / §6.4.2:

- Root Cause field + 6M Root Cause Category lookup (Man/Machine/Method/
  Material/Measurement/Environment), separate from Deviation Detail/Category
- "Corrective Action Required?" Yes/No gate on every NCR with a required
  justification
- Corrective action plan with owner + due date; owner is notified by email
- Effectiveness verification (result, notes, server-stamped verifier/date)
  required before an NCR can close when corrective action is required —
  costing returns 409 listing the missing pieces
- Recurring-issue flag with bidirectional NCR-to-NCR links; prior NCRs show
  a warning when later NCRs reference them
- Dashboard metrics: % root cause completed, % CAPA verified effective,
  avg CAPA close time, overdue CAPA count, NCRs by root cause category
- CAPA section in the NCR detail UI, printable PDF, CSV export, and the
  vw_ncr_full Power BI view; admin list manager for root cause categories
- Migrations 0003 (schema + seeded 6M lookup) and 0004 (view refresh);
  demo seed data exercises every metric

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/alembic/versions/0003_capa_fields.py

@@ -0,0 +1,112 @@
+"""CAPA fields for API Q1 §5.9.1.2 / §6.4.2
+
+Revision ID: 0003
+Revises: 0002
+Create Date: 2026-08-04
+
+Adds root cause capture, the corrective-action gate (required? +
+justification), the corrective action plan (owner + due date),
+effectiveness verification, the recurring-issue flag with NCR-to-NCR
+links, and the 6M root-cause category lookup (seeded here so upgraded
+deployments have the standard values without re-running app.seed).
+"""
+from alembic import op
+import sqlalchemy as sa
+
+revision = "0003"
+down_revision = "0002"
+branch_labels = None
+depends_on = None
+
+MYSQL = {"mysql_charset": "utf8mb4", "mysql_collate": "utf8mb4_unicode_ci"}
+
+SIX_M_CATEGORIES = ["Man", "Machine", "Method", "Material", "Measurement", "Environment"]
+
+
+def upgrade() -> None:
+    op.create_table(
+        "root_cause_categories",
+        sa.Column("id", sa.Integer(), primary_key=True, autoincrement=True),
+        sa.Column("name", sa.String(100), nullable=False, unique=True),
+        sa.Column("is_active", sa.Boolean(), nullable=False, server_default=sa.text("1")),
+        **MYSQL,
+    )
+    categories = sa.table(
+        "root_cause_categories", sa.column("name", sa.String), sa.column("is_active", sa.Boolean)
+    )
+    op.bulk_insert(categories, [{"name": n, "is_active": True} for n in SIX_M_CATEGORIES])
+
+    op.create_table(
+        "ncr_links",
+        sa.Column(
+            "ncr_id", sa.Integer(), sa.ForeignKey("ncrs.id", ondelete="CASCADE"), primary_key=True
+        ),
+        sa.Column(
+            "related_ncr_id",
+            sa.Integer(),
+            sa.ForeignKey("ncrs.id", ondelete="CASCADE"),
+            primary_key=True,
+        ),
+        **MYSQL,
+    )
+
+    op.add_column("ncrs", sa.Column("root_cause", sa.Text(), nullable=True))
+    op.add_column(
+        "ncrs",
+        sa.Column(
+            "root_cause_category_id",
+            sa.Integer(),
+            sa.ForeignKey("root_cause_categories.id"),
+            nullable=True,
+        ),
+    )
+    op.add_column("ncrs", sa.Column("corrective_action_required", sa.Boolean(), nullable=True))
+    op.add_column(
+        "ncrs", sa.Column("corrective_action_justification", sa.Text(), nullable=True)
+    )
+    op.add_column("ncrs", sa.Column("corrective_action_plan", sa.Text(), nullable=True))
+    op.add_column(
+        "ncrs",
+        sa.Column(
+            "corrective_action_owner_id", sa.Integer(), sa.ForeignKey("users.id"), nullable=True
+        ),
+    )
+    op.add_column("ncrs", sa.Column("corrective_action_due_date", sa.Date(), nullable=True))
+    op.add_column("ncrs", sa.Column("corrective_action_opened_at", sa.DateTime(), nullable=True))
+    op.add_column("ncrs", sa.Column("effectiveness_result", sa.String(20), nullable=True))
+    op.add_column("ncrs", sa.Column("effectiveness_notes", sa.Text(), nullable=True))
+    op.add_column("ncrs", sa.Column("effectiveness_verified_at", sa.DateTime(), nullable=True))
+    op.add_column(
+        "ncrs",
+        sa.Column(
+            "effectiveness_verified_by_id",
+            sa.Integer(),
+            sa.ForeignKey("users.id"),
+            nullable=True,
+        ),
+    )
+    op.add_column(
+        "ncrs",
+        sa.Column("is_recurring", sa.Boolean(), nullable=False, server_default=sa.text("0")),
+    )
+
+
+def downgrade() -> None:
+    for column in (
+        "is_recurring",
+        "effectiveness_verified_by_id",
+        "effectiveness_verified_at",
+        "effectiveness_notes",
+        "effectiveness_result",
+        "corrective_action_opened_at",
+        "corrective_action_due_date",
+        "corrective_action_owner_id",
+        "corrective_action_plan",
+        "corrective_action_justification",
+        "corrective_action_required",
+        "root_cause_category_id",
+        "root_cause",
+    ):
+        op.drop_column("ncrs", column)
+    op.drop_table("ncr_links")
+    op.drop_table("root_cause_categories")