SIMD-0560: Mandatory Delegation of Surplus Lamports

[staccDOTsol]

Summary

This SIMD proposes that the runtime sweep every lamport above an account's
rent-exempt minimum into approved liquid staking positions, unwinding
automatically on debit and on account close. Holding undelegated SOL above
the rent floor becomes a state the protocol no longer represents.

What this PR is actually for

The proposal is submitted in the expectation of rejection, and says so in its
front matter's own terms: its success criterion is not feature-gate
activation but a rejection rationale articulated at the same rigor as the
objections the document itself enumerates (enshrined-cartel layering, float
conservation/bank-run dynamics, yield convergence to zero at forced full
participation, and the rebasing reduction). The protocol currently holds an
implicit, unwritten position on what idle SOL is for; this PR is a forcing
function to get that position written down.

Reviewers are accordingly asked to reject it well.

Notes

• Numbered 0560 on the assumption this PR takes the next number; will
  renumber to match the actual PR number if it lands differently.
• Passes markdownlint and the custom SIMD linter with 0 errors.
• Appendix A (the wSOL extension) is deliberately severable; Appendix B
  lists open empirical items with exact-figure methodology.
• Alternatives Considered, item 1 (inactivity-gated sweep of terminal
  program state) is the salvageable artifact if the body dies as intended.

[staccDOTsol]

I’m so miffed I have to do a discussion rather than opening a pr. lol.