Remove legacy pc tables, fix ASP issues, update dashboard APIs

Database changes (run sql/migration_drop_pc_tables.sql on prod):
- Drop pc, pc_backup_phase2, pc_to_machine_id_mapping tables
- Rename pcid columns to machineid in machineoverrides, dualpathassignments, networkinterfaces
- Recreate 9 views to use machines.machineid instead of pcid
- Clean orphaned records and add FK constraints to machines table

ASP fixes:
- editprinter.asp: Fix CLng type mismatch when no printerid provided
- includes/sql.asp: Remove AutoDeactivateExpiredNotifications (endtime handles expiry)
- includes/leftsidebar.asp: Update fiscal week banner styling, remove dead Information link
- charts/warrantychart.asp: Use vw_warranty_status instead of pc table

Dashboard API renames (naming convention):
- shopfloor-dashboard: Update to use apishopfloor.asp, apibusinessunits.asp
- tv-dashboard: Rename api_slides.asp to apislides.asp

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

editprinter.asp

@@ -45,7 +45,13 @@
 	newvendorname = Trim(Request.Form("newvendorname"))
 
 	' Validate required fields
-	If Not IsNumeric(printerid) Or CLng(printerid) < 1 Then
+	If printerid = "" Or Not IsNumeric(printerid) Then
+		objConn.Close
+		Response.Redirect("displayprinters.asp?error=INVALID_PRINTER_ID")
+		Response.End
+	End If
+
+	If CLng(printerid) < 1 Then
 		objConn.Close
 		Response.Redirect("displayprinters.asp?error=INVALID_PRINTER_ID")
 		Response.End