docs(cli): rewrite cli/init.md for 5-step wizard (post-netclaw-dev/netclaw#1368)

[Aaronontheweb]

Context

Tracks the rewrite of src/content/docs/cli/init.md after netclaw-dev/netclaw#1368 ships in a stable release.

Current

11-step reference (steps 3–10 = channels / search / browser / identity×6 / ext-skills / feeds / exposure / webhooks). "Before you begin" asks for channel tokens. ~21 init screenshots keyed to old step numbering.

Should become

5 steps:

1. LLM Provider — picker, OAuth/API-key, connectivity probe, model select
2. Identity — agent name, operator name, communication style, timezone (4 fields only)
3. Security Posture — Personal / Team / Public
4. Enabled Features — toggles; skipped for Personal posture
5. Health Check — validates → auto-launches netclaw chat on success; summary + netclaw doctor pointer on failure

Add re-running on existing install section: action menu (Redo Identity / Open config editor / Start over / Cancel); Start over double-confirms (setup-only vs full reset).

"Before you begin" needs only provider credentials. "After init" → point to netclaw config.

Screenshots or tapes needed

init-01-provider-list, init-01-provider-ollama, init-01-endpoint, init-01-model-select, init-02-identity (4-field form), init-03-security-posture, init-04-feature-selection (Team posture), init-05-health-check (spinner), init-05-health-check-success (auto-launch message), init-existing-action-menu (4 options), init-existing-start-over-confirm (setup-only vs full).

All captures gated on stable release containing netclaw-dev/netclaw#1368. Until then, leave <!-- capture after release --> placeholders.

Acceptance criteria

• Accurate 5-step reference; no channels / search / browser / skills / feeds / exposure as init steps
• Re-entry action menu documented (Redo Identity / Open config editor / Start over / Cancel)
• Health check auto-launch on success documented
• "After init" callout links to netclaw config
• Stale screenshots replaced (no broken <img> refs)
• "Before you begin" no longer asks for channel tokens

Dependencies

• Stable release tag containing feat(init,config): simplified init, rebuilt config TUI, canonical channel-ID resolution netclaw#1368 (for screenshot capture and final <img> insertion)
• Sub-issue Update exposure/pairing docs and homepage hero copy #13 (screenshot re-capture campaign) must complete before <img> tags are filled in

Part of #55