Add printer lifecycle fields and printer log

- Printer: bought_at, last_maintenance_at, decommissioned_at (all Date, nullable)
- PrinterLog: per-printer timestamped text entries (CASCADE delete)
- Migration 0003: adds columns + printer_logs table
- /printers/{id}: detail page showing lifecycle info + scrollable log
- POST /printers/{id}/log: add a log entry via modal form
- Printer names in list are now links to the detail page
- Add Printer modal includes optional purchase date

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

alembic/versions/0003_printer_lifecycle_and_logs.py

@@ -0,0 +1,39 @@
+"""printer lifecycle fields and printer_logs table
+
+Revision ID: 0003
+Revises: 0002
+Create Date: 2026-06-18
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0003"
+down_revision: Union[str, None] = "0002"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column("printers", sa.Column("bought_at", sa.Date(), nullable=True))
+    op.add_column("printers", sa.Column("last_maintenance_at", sa.Date(), nullable=True))
+    op.add_column("printers", sa.Column("decommissioned_at", sa.Date(), nullable=True))
+
+    op.create_table(
+        "printer_logs",
+        sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
+        sa.Column("printer_id", sa.Integer(), nullable=False),
+        sa.Column("message", sa.Text(), nullable=False),
+        sa.Column("created_at", sa.DateTime(), nullable=False, server_default=sa.text("CURRENT_TIMESTAMP")),
+        sa.ForeignKeyConstraint(["printer_id"], ["printers.id"], name="fk_log_printer", ondelete="CASCADE"),
+        sa.PrimaryKeyConstraint("id"),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("printer_logs")
+    op.drop_column("printers", "decommissioned_at")
+    op.drop_column("printers", "last_maintenance_at")
+    op.drop_column("printers", "bought_at")