feat(translate): move write settings to Target Config tab + fix datasource name lookup

Fixes:
- Move batch size, upsert strategy, include source reference
  from Config tab to Target Config tab (Write Settings section)
- Fix 'Dataset #26' fallback — look up real datasource name
  via API when source_table is not saved in job data
- Persist include_source_reference in save payload and
  restore from job data on load (was a pre-existing gap)

QA review fixes:
- Update @BRIEF contracts for both tabs
- Fix import indentation in +page.svelte

Other: help tooltips on translate pages, flow hint on list page,
git migration manager components, dashboard hub pages,
migration settings pages

.opencode/opencode.jsonc

@@ -1,5 +1,8 @@
 {
   "$schema": "https://opencode.ai/config.json",
+  "experimental": {
+    "mcp_timeout": 300000
+  },
   "mcp": {
     "chrome-devtools": {
 	"type": "local",