feat(fusion_plating_jobs): auto-pause cron for stale in-progress steps

Plan tasks P2.4 + P2.5 batched.

Adds _cron_autopause_stale_steps method on fp.job.step + 30-min cron
registration. Flips in_progress steps idle > threshold to paused with
a chatter audit ("Auto-paused after Nh idle. Resume from the tablet
when work continues.").

Threshold from ir.config_parameter:
    fp.shopfloor.autopause_threshold_hours  (default 8.0)

Recipe nodes opt out via fusion.plating.process.node.long_running
(added in P2.1) — useful for 24h bakes and multi-shift soaks.

Fixes the 411-hour ghost timer that motivated the redesign. Doesn't
replace the existing nudge crons — those still notify the supervisor;
this one actually pauses the timer.

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

fusion_plating/fusion_plating_jobs/models/fp_job_step.py

@@ -151,6 +151,62 @@ class FpJobStep(models.Model):
             step.blocker_jump_target_model = False
             step.blocker_jump_target_id = 0
 
+    # ==================================================================
+    # Shop-Floor auto-pause cron (Phase 2 — tablet redesign)
+    # ==================================================================
+    @api.model
+    def _cron_autopause_stale_steps(self):
+        """Flip in_progress steps idle > threshold to paused.
+
+        Threshold read from ir.config_parameter
+            fp.shopfloor.autopause_threshold_hours  (default 8.0)
+
+        Recipes can opt out per node via
+            fusion.plating.process.node.long_running  (Phase 2 — P2.1)
+
+        Fixes the 411-hour ghost timer that bit us on the original tablet
+        when an operator started a step and never tapped Finish. Posts an
+        audit chatter entry on the step so the operator can see what
+        happened when they resume.
+        """
+        from datetime import timedelta
+        threshold = float(
+            self.env['ir.config_parameter'].sudo()
+            .get_param('fp.shopfloor.autopause_threshold_hours', 8)
+        )
+        deadline = fields.Datetime.now() - timedelta(hours=threshold)
+        domain = [
+            ('state', '=', 'in_progress'),
+            ('date_started', '<', deadline),
+            '|',
+                ('recipe_node_id', '=', False),
+                ('recipe_node_id.long_running', '=', False),
+        ]
+        stale = self.search(domain)
+        paused = 0
+        for step in stale:
+            try:
+                step.button_pause()
+                step.message_post(body=Markup(
+                    "<b>Auto-paused</b> after %.1fh idle. "
+                    "Resume from the tablet when work continues."
+                ) % threshold)
+                _logger.info(
+                    "Auto-paused step %s (%s) after %.1fh idle",
+                    step.id, step.name, threshold,
+                )
+                paused += 1
+            except Exception:
+                _logger.exception(
+                    "Auto-pause failed for step %s — skipping", step.id,
+                )
+        if paused:
+            _logger.info(
+                "_cron_autopause_stale_steps: paused %d step(s) "
+                "(threshold %.1fh)", paused, threshold,
+            )
+        return paused
+
     # NOTE: the actual button_start override lives further down (~line
     # 876) where it merges Sub 13 predecessor gate + Policy B Contract
     # Review auto-open + Sub 8 Racking auto-open + the receiving soft