Saved template overrides never reach outgoing email

[NathanTarbert]

Template overrides save and preview correctly — PUT /api/templates/[slug] persists through prisma.templateOverride.upsert (apps/web/src/app/api/templates/[slug]/route.ts:125), and the editor previews the unsaved draft (apps/web/src/app/settings/templates/page.tsx:96). What a saved override does not do is reach an outgoing email: the send path still renders the packaged defaults, so an author edits a template, sees the change in the preview, saves it, and every email that goes out is unchanged.

The UI is honest about it today — the save toast and the page description both say so — but they point readers at an issue that no longer exists, so the explanation dead-ends at a 404.

What to do

• Make the email send path read TemplateOverride and fall back to the packaged default when no override exists
• Re-point the two user-facing strings at this issue (page.tsx:138, page.tsx:177)
• Re-point the eleven test docblocks and the middleware.ts:14 comment that reference the removed issues
• Drop "(preview only)" from the template list badge at page.tsx:221 once sending honours overrides

Acceptance

• A saved override changes the subject and body of the next outgoing email of that type
• Removing the override restores the packaged default
• A test covers override → send, and default → send
• No string in apps/web or the test suite points at a removed issue number