Feat/tool call timestamps

[krishnaclouds]

Summary

Adds visibility into how long tool calls take inside the TUI — both per-call and at the session level.

• Per-tool timing. Every tool call now shows its start time and elapsed duration right next to it (HH:MM:SS · 234ms for finished, HH:MM:SS · running 12.3s for in-flight). Live-ticks at 1Hz while running, freezes on completion. Tool calls running longer than 30s flip to the theme's warning color so slow calls stand out.
• Sidebar total. The session sidebar's Context block gains a in tools line that sums execution time across every tool call in the session, ticking live while any tool is running.
• Toggle. Bound to the existing timestamps setting. Adds /timing and /toggle-timing slash aliases alongside the existing /timestamps. Renames the menu entry to "tool timing." Default changes from hide → show; users with an explicit prior choice keep it (kv persistence).
• Refactor. A small routes/session/timing.ts module owns SLOW_TOOL_MS, the Elapsed type, and the format helper — replaces three copies of the timing-string builder across InlineTool/BlockTool with one call.
• Helper. New Locale.clockTime(ms) produces 24-hour HH:MM:SS.

What changed and why?

Test Plan

• bun test packages/opencode/test/util/locale.test.ts — passes (new clockTime cases)
• bun turbo typecheck — passes (pre-push hook, all 5 packages green)
• Run a fast tool in a session → inline row renders HH:MM:SS · and freezes on completion
• Run a slow tool (>30s) → inline timing turns warning-colored while running, locks to muted on completion
• Sidebar Context block shows in tools and gains (running) while a tool is in-flight, ticking once per second
• /timing, /toggle-timing, and /timestamps all toggle visibility; preference persists across sessions
• Block-style tools (spinner variants) render timing inside the spinner label

Checklist

• Tests added/updated — unit coverage for Locale.clockTime; reactive hooks (useElapsed, toolTime) intentionally not unit-tested (no lightweight harness for this Solid-on-TUI renderer; tracked as known testing debt)
• Documentation updated (if needed) — no docs reference the prior /timestamps UX; new aliases discoverable via the existing command palette
• CHANGELOG updated (if user-facing) — toggle default flip from hide → show is the only behavior change for existing users; worth a one-liner if this repo keeps a CHANGELOG