feat: polish tools and session UI

[teedole]

Summary

• Polish Tools & MCP with a responsive 2×2 summary, deterministic table column budgets, contained long-name overflow, and explicit Error / OK / Unknown status badges in both the table and detail drawer.
• Add compact session-list timestamps and guard report/share backdrops so only direct backdrop clicks dismiss their dialogs.

is_error = null intentionally maps to Unknown. The archive does not expose an independent pending state, so presenting Pending would invent information.

Why

The Tools page could widen unpredictably around long MCP names, tool outcomes were ambiguous, session rows lost useful date context, and clicks inside report/share dialogs could bubble into their dismissal backdrops.

Validation

• just check passes: 658 tests, TypeScript, Biome, and the darwin-arm64 distribution staging smoke.
• New behavior has focused tests. No existing test was weakened or deleted to make this pass.
• Adversarial PR-style review is clean after increasing the status-column budget to preserve the full Unknown label.
• Synthetic-archive browser validation at 1440px light and 1024px/680px dark: long names truncate, table overflow remains contained, the 2×2 summary holds at 680px, all status labels remain readable, and the console reports zero errors.
• Browser behavior validation: the Unknown detail drawer renders the same status; inner report-sheet clicks keep it open; a direct backdrop click dismisses it.

Archive schema

The baseline is LATEST_SCHEMA_VERSION in src/db.ts. Check one:

• This change does not touch the archive schema.
• This change bumps the schema. It ships the migration, and the summary above says what happens to archives created before it.

[gemini-code-assist]

Code Review

This pull request introduces relative time formatting helpers, dynamic table column layouts, and an improved tool call status badge, along with comprehensive unit tests. The feedback highlights a critical performance optimization: caching the Intl.DateTimeFormat and Intl.RelativeTimeFormat instances at the module level to prevent expensive re-instantiations during table renders.

[teedole]

Addressed review findings; inline replies include the implementation and validation evidence.

[teedole]

Validator follow-up complete at signed tip c670831.

• The no-duration call-status column is 12 percent, and tests pin both duration layouts.
• Removed the dead has-duration class.
• Unknown status now has keyboard/screen-reader-visible explanatory text.
• Compact relative time rolls 24h into 1d.

Evidence: focused UI suites and adversarial re-review clean; combined #73-#79 gate 781/781 plus TypeScript, Biome, distribution smoke, and headed desktop/mobile rendering.