Backend: consolidate controllers, align service permission checks,
bulk task insert, overdue marking job with notifications, fix false 403
on accepting self-created tasks, review approval push + reopen cancel
notices, home alert notifications, drop dead signal resolve endpoint.

Frontend: task table pagination + row memo, a11y passes, sprint form
preview, adaptive dialog width, global back button, consolidated signal
and quality-gate UI, plain-language copy, uniform row heights.

Tests/docs: backend 385 + frontend 229 tests green; CHANGELOG documents
all 10 improvements; E2E baseline held (1 pre-existing failure).