docs: add user manual documentation (#979)
* docs: add user manual documentation
Add comprehensive user manual covering getting started, provider management,
extensions (MCP/prompts/skills), proxy configuration, and FAQ sections.
Includes screenshots and a README index.
* fix(docs): align user manual with v3.10.3 codebase
- Add OpenCode as 4th supported app throughout all docs
- Fix proxy default port 15762 → 15721
- Update Claude presets (9 → 26), Codex (3 → 10), Gemini (3 → 7)
- Add OpenCode presets (25 entries)
- Fix timeout defaults and ranges (stream first byte 60s/90s, etc.)
- Fix circuit breaker defaults with per-app values (Claude vs general)
- Fix Skills support: all 4 apps, not just Claude/Codex
- Remove non-existent Gemini authMode field
- Fix prompt deletion behavior: enabled prompts cannot be deleted
- Remove non-existent Legacy deeplink protocol, use V1 only
- Fix DB table names (usage_logs → proxy_request_logs) and add missing tables
- Fix migration version v3.8.0 → v3.7.0
- Add missing V1 deeplink parameters (config, configFormat, etc.)
- Update doc version v3.9.1 → v3.10.3
- Add claude-opus-4-1 to pricing table
- Fix recovery wait time range 10-300 → 0-300
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Co-authored-by: Jason <farion1231@gmail.com>
Dex Miller