Release v0.2.6: truthful analytics and resilient guidance

[thrr87]

Summary

• make rolling analytics ranges end at the Mac's current instant while preserving exact selected ranges
• render truthful Account Token Activity intervals across rolling, selected, and current-window ranges
• merge multi-Mac account readings without double-counting and preserve counter breaks, missing time, observed zero, and UTC fallback semantics
• add interval details, zoom-aware aggregation, and accessible chart descriptions
• calculate Suggested Pace without history and restore Runway and Current Estimate after compatible account gaps
• prepare app version 0.2.6 (build 7)

Verification

• DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer xcrun swift test — 559 tests passed
• ./Scripts/build-app.sh — release build succeeded and reports version 0.2.6 (build 7)
• integrated manual QA passed for every issue from Analytics: anchor rolling presets to now in Mac-local time #47 through Guidance: restore Runway and Current Estimate after long account gaps #59, including all Account Token Activity ranges, Current window future emptiness, selection/evidence, zoom/accessibility, Suggested Pace, Runway, and Current Estimate

Issues

Closes #46
Closes #47
Closes #48
Closes #49
Closes #50
Closes #51
Closes #52
Closes #53
Closes #54
Closes #55
Closes #56
Closes #57
Closes #58
Closes #59