fix(jobs): qty gate false-positive on paperwork / first steps

The qty gate I added refused Finish on steps where qty_at_step > 0,
to force operators to move parts forward first. But the first-step
seed in _compute_qty_at_step gives the earliest non-terminal step
a notional qty = job.qty — a UI hint, not actual parked parts.
Paperwork steps (Contract Review, Inspection-by-paperwork, etc.)
sit on that seed, and the gate was blocking Finish with a misleading
error.

Fixes:
- button_finish gate now checks for REAL incoming moves before
  refusing. Seed-only qty (no incoming_move_ids filtered to non-
  self-loop) is exempt.
- _fp_record_one_piece_auto_move detects seed-only qty and bulk-
  moves ALL parts in one shot to the downstream step. Correct for
  paperwork / first steps where parts don't physically wait
  per-piece — one click finishes the paperwork and pushes the whole
  batch forward.

For steps with REAL incoming moves (parts actually moved here via
a Move record), the original gate semantics still apply: qty == 1
auto-moves one part; qty > 1 raises with the "use Complete 1 → Next
or Move…" message.

Verified on entech: Contract Review with seed qty=6 now finishes
cleanly, bulk-moving all 6 parts to the next step in one move.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion_plating/fusion_plating_jobs/__manifest__.py

@@ -3,7 +3,7 @@
 # License OPL-1 (Odoo Proprietary License v1.0)
 {
     'name': 'Fusion Plating — Native Jobs',
-    'version': '19.0.8.20.5',
+    'version': '19.0.8.20.6',
     'category': 'Manufacturing/Plating',
     'summary': 'Native plating job model — replaces mrp.production / mrp.workorder bridge.',
     'author': 'Nexa Systems Inc.',