Add WakaTime rich AI metadata sync mode

[SuvenSeo]

Goal

Add an opt-in richer WakaTime sync mode for AI coding metadata where WakaTime supports it.

Why

The current sync is intentionally conservative. A richer mode can be useful if users explicitly want more AI coding analytics.

Acceptance Criteria

• Add --wakatime-mode conservative|rich or equivalent.
• Conservative mode remains the default.
• Rich mode documents exactly what metadata leaves the machine.
• Add tests for payload construction without making network calls.
• README and privacy docs are updated.