🤖 feat: add timing stats indicator in workspace sidebar

[ThomasK33]

Add a new Stats tab in the right sidebar that displays timing statistics for streaming sessions. The tab shows elapsed time, time to first token (TTFT), model inference time, and tool execution duration.

Features

• Stats tab in right sidebar - New tab after Review with keyboard shortcut Cmd/Ctrl+3
• Session/Last Request toggle - Switch between aggregate session stats and last request details
• Tab title shows duration - Like Costs shows "$2.71", Stats shows total session time (e.g., "Stats 12s")
• Aggregated timing stats - Progress bar + component breakdown table
• Per-model breakdown - Each model gets its own timing section with mini progress bar
• Live updates - Timer updates every second during active streams
• Persistent across restarts - Session timing stats saved to localStorage

Screenshot

The Stats tab displays timing information in a format consistent with the Costs tab:

┌─────────────────────────────────────────┐
│ Costs $2.71    Review    Stats 12s      │
├─────────────────────────────────────────┤
│ Timing ●  [Session] [Last Request]  12s │
│ 1 response                              │
│ ████████████████████░░░░░              │
│                                         │
│ Component              Duration    %    │
│ ● Avg. Time to First Token  3.1s   —   │
│ ● Model Time               9.5s   79%  │
│ ● Tool Execution           2.5s   21%  │
│                                         │
│ By Model                                │
│ Sonnet 4                   12s (1 req)  │
│ ████████████████████░░░░░              │
│ TTFT: 3.1s  Model: 9.5s  Tools: 2.5s   │
└─────────────────────────────────────────┘

Implementation

• StatsTab component - Displays timing stats with toggle and per-model breakdown
• StreamingMessageAggregator - Tracks timing data (startTime, firstTokenTime, toolExecutionMs)
• WorkspaceStore - Exposes StreamTimingStats and SessionTimingStats via sidebar state
• localStorage persistence - Session stats persist across app restarts

---

Generated with mux

[ThomasK33]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. More of your lovely PRs please.

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[ThomasK33]

@codex review

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💡 Codex Review

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[ThomasK33]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Hooray!

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