fix: correct agent-facing instructions in SKILL.md and init/mine docs

[sha2fiddy]

Summary

Fixes #534 — three issues in agent-facing documentation that cause failures when agents follow the instructions:

• SKILL.md: Changed mempalace --version to mempalace status — the CLI has no --version flag, so the prerequisite check always failed
• init.md: Changed mempalace init <dir> to mempalace init --yes <dir> — without --yes, agents hit EOFError because there is no TTY for interactive prompts
• mine.md: Added a prerequisite note that mempalace init must be run before mining, so agents don't attempt to mine into an uninitialized palace

Test plan

• Verify mempalace status works as an install check (returns non-zero if not installed)
• Verify mempalace init --yes <dir> completes non-interactively
• Confirm mine instructions now reference the init prerequisite

[web3guru888]

sha2fiddy's fixes are all correct on their merits — the three substitutions (mempalace status in SKILL.md, --yes in init.md, and the mine.md prerequisite note) are exactly right.

This overlaps with #559 (adiKhan12), submitted at roughly the same time and addressing the same three issues — worth flagging for @milla-jovovich to pick an approach. The key difference: #560 is a clean docs-only fix, while #559 goes a step further and adds actual argparse support so --version works as a real CLI flag (plus behavioral tests). If the project wants to close the underlying code gap, #559 does that; if docs-only is preferred, #560 is lighter and gets the job done.

Either way, the prerequisite call-out in mine.md and the --yes flag for agent contexts are good catches that should land regardless of which PR is merged.

[jphein]

Note: #562 includes overlapping fixes to SKILL.md and init instructions.

[sha2fiddy]

Closing — issue #534 was closed by the maintainer, and the remaining work is tracked in #632.