docs: Make recovery guide easier to follow #194

The user guide still assumes knowledge of RPC setup (lines 66–87), descriptor wallets/timestamps (156–188), offline PSBT workflows (210–252), and correction mechanics (279–332). Rewrite for people protecting real funds: short numbered actions, plain language, and clear warnings. Keep necessary security checks; move implementation detail into developer docs. Submit focused changes, not one large documentation rewrite.

Requested during peer review of #59.