Receiving: fix a receipt after the fact, and stop 'receiving' sales tax

Two receiving realities the app now respects: people fat-finger quantities at the dock, and nobody signs for sales tax.

Corrections. Every logged receipt has Edit and Delete now. Edit reopens the same shipment form seeded with that receipt's quantities — and the Remaining column correctly excludes the receipt you're fixing, so its own units don't double-count against the order. Delete asks first, then removes the receipt entirely. Either way the PO's status walks honestly in both directions: shrink the only receipt and Received steps back to Partial; delete it and the PO returns to Issued. On stock POs, corrections keep the warehouse honest too — the inventory ledger is append-only, so a correction writes reversing entries against the original receipt rows and restates from the fixed quantities. On-hand counts and weighted-average cost stay right, and the paper trail shows the fix.

Charge lines. Mark any PO line as a charge — sales tax, freight, permit fees — straight from the Lines tab, even after the PO is issued (it's a receiving decision, not a financial edit; the amount still counts in the PO total and committed cost). Charge lines:

• disappear from the Log Shipment form — no more entering "1 sales tax received",
• show not received instead of a remaining quantity on the Lines tab,
• and stop gating the fully-received status: receive the actual goods and the PO reads Received, tax line and all.

Existing lines whose description says "sales tax" were flagged automatically. On the job cost side, a charge line's value lands as actual cost the moment its PO finishes receiving, so committed and actual converge instead of tax showing as an open commitment forever.