Release process bootstrap

Highlights

• Weekly main → production promotion flow with auto-generated changelog from Conventional Commits.
• New /changelog page rendering markdown files under content/changelog/.
• db:reset now refuses to run against a managed-host DATABASE_URL unless explicitly opted in.

Changes

Features

• feat(rota): show "Approved" badge once timesheet is signed off.
• feat(staff): coworker list per day in the staff view.
• feat(employees): date-of-birth field on employee profiles.
• feat(admin): inbox merged into the admin dashboard at /admin#inbox.

Fixes

• fix(missing-timesheets): exclude shifts that already have a timesheet.
• fix(rota): time-off range spans every day in the viewer's timezone.
• fix(login): marketing header logo visible on mobile in dark mode.
• fix(shifts): deleting a shift now also deletes its timesheet.

Chores

• chore(seed): single linked employee vinicius-mdias@hotmail.com.
• chore(marketing): drop pilot section + brand mentions.