fix(scan): Fix-mode scanner + dialog suppression + cancel/timer + importer revive

- scan.jsx: app.beginSuppressDialogs() + clean quit (no AE hang on font/footage
  dialogs); FIX-mode branch parses frl_c(x)t/m(y) layer names → scenes by c(x);
  flexible/mockup keep comp-based walk; FR_SCAN_MODE selects.
- render-svc: scan job carries project mode; cancel endpoint + node watchdog that
  kills AE on cancel; parseObjectURL handles minio:// (bucket in host); scan with
  no template fails cleanly; status guards so late results can't un-cancel.
- content importer: revive soft-deleted scenes instead of duplicate-inserting
  (fixes scenes_project_id_key unique violation); orphan diff ignores deleted.
- admin: scan dialog gets project-type picker + elapsed timer + Cancel button.
- node-agent: AE-2026 wiring (host port 5010, host-reachable presign endpoint),
  FR_SCAN_MODE plumbing. docs/aep-template-convention.md: per-type naming + bundles.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/db/migrations/28_render_scan_mode.sql

@@ -0,0 +1,8 @@
+-- =====================================================================
+-- RENDER SCHEMA — scan jobs carry the project TYPE so scan.jsx parses with
+-- the right convention (fix = layer-name encoding, flexible/mockup = comps).
+-- =====================================================================
+
+SET search_path TO render, public;
+
+ALTER TABLE scan_jobs ADD COLUMN IF NOT EXISTS mode TEXT NOT NULL DEFAULT 'flexible';