refactor(jobs): drop index=True on part_catalog_id for consistency

Code review noted this was asymmetric — only part_catalog_id had
explicit index=True among the 5 new fields, and Phase 1 core fp.job
relies on Odoo's implicit FK btree for ALL Many2ones (no explicit
indexes). Removed for consistency.

Important I2 (no explicit ondelete= policies) is deferred to a
phase-end polish task that addresses both Phase 1 core and Phase 2
extension fields uniformly.

Manifest 19.0.1.1.0 → 19.0.1.1.1.

Part of: native job model migration (spec 2026-04-25)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion_plating/fusion_plating_jobs/models/fp_job.py

@@ -19,7 +19,6 @@ class FpJob(models.Model):
     part_catalog_id = fields.Many2one(
         'fp.part.catalog',
         string='Part',
-        index=True,
     )
     coating_config_id = fields.Many2one(
         'fp.coating.config',