Refocus trainer dashboard on actionable stats

[OwenTanzer]

Summary

• Move Needs Attention and Recently Worked to the top of the trainer dashboard, right after the header — these are the stats a trainer actually uses to decide what to do next.
• Remove the Career Highlights section entirely (training logs, logs this week/month, milestones completed, skills worked on total).
• Remove the Skills You've Worked Most section entirely.
• Replace the retrospective "A look back at your training career..." copy with a direct, operational description of the page.
• Remove the now-dead computations backing the removed sections (totalLogs, logsThisWeek, logsThisMonth, milestonesCompleted, skillsWorkedOnTotal, mostWorkedSkills, the SkillWorkedCount type, and the now-unused daysAgoLocalDate helper) from useTrainerHistoryStats.

Your Dogs, Success Rate, and Final Evaluation Outcomes are unchanged in content, just reordered below the actionable sections.

Why

Issue #27's follow-up scope asked for a prioritization/subtraction pass on the existing stats page — put actionable statistics first, drop the decorative career-retrospective sections, and don't replace them with equally decorative summaries. This PR does exactly that without adding any new analytics.

Validation

• npm run build — production TypeScript and Vite build passed
• npm test — 28 tests passed
• npm run lint — passed with the same 3 pre-existing warnings as main (unrelated to this change)

Closes #27

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Generated by Claude Code

[OwenTanzer]

One small behavioral mismatch remains before merge: the follow-up scope asks for refined/actionable statistics to appear first, but TrainerHistory still initializes refinedRate to false, so Overall is the default success-rate view. Please change the initial state to true (and preferably place the Refined button before Overall so the visual order matches the default). After that, this looks ready to merge.