Journal: UX + code polish follow-ups from #79 review

[manucompiles]

From the #79 code review (R9, R19, R20, R21, R25, R26, R27, R30 - all Suggest-grade except the first two Warns which are low-impact for a single user).

• MindWidget items are keyed/cleared by exact text: duplicate texts collide (duplicate React keys; clearing one clears all copies). Key by index, or reject duplicate adds.
• The 30s poll can briefly clobber an optimistic plan-task toggle (self-heals next poll; nothing persisted wrongly). Pause polling while a toggle is in flight.
• 'Today so far' shows TODAY's habit count on past dates. Hide the habits row when viewing a past day, or fetch that day's check-ins.
• Template seeding never removes rows for Keys deleted from code (orphan rows keep rendering in exports). Flag or clean deliberately.
• lib/api.ts searchOpenTasks is exported but unused (plan combobox filters the loaded list locally - documented decision). Delete or keep deliberately.
• Journal/mood controllers project with anonymous objects where HabitResponse/TimeEntryResponse set a named-record precedent.
• MoodCheckinsController Create uses CreatedAtAction(nameof(List)) - Location header points at the bare collection (same family as Fix: CreatedAtAction in ProjectsController points to wrong route #17).
• lib/journal.ts timeOfDayLabel near-duplicates time.ts clockLabel (formats differ deliberately); add a one-line why-not-reused comment.