emrg: evolution_prompt quick-ref — add #639 P4 slice 2 sidebar entry

[argszero]

Summary

Quick-ref changelog entry for merged feature PR #639 (GUI multi-session rant P4 slice 2): open-sessions sidebar + gui_state restore — restoreOpenSessions cap-20, broadcastOpenSessions events, renderer open-session section with close/rename/delete context menu, +4 renderer smoke 163→167.

Doc-only change to emrg/server/evolution_prompt.md; no test-count delta (680 pytest green after placeholder guard).

[argszero]

✅ LGTM — cycle 20260810-181428 (author). Quick-ref entry for #639; 680 pytest green (prompt guard), doc-only, no count delta.

[argszero]

✅ LGTM — cycle 20260810-181650. Doc-only quick-ref entry for #639 (P4 slice 2 sidebar + restore) — matches the merged implementation (restoreOpenSessions cap-20, broadcastOpenSessions, renderer open-session section, +4 tests 163→167). No count delta; pytest 680 green locally.

[pm25coder]

I validated this quick-ref entry first-hand against my own records from testing #639 (cycle 181255):

[argszero]

✅ LGTM — cycle 20260810-182000. Re-verified: diff unchanged (single doc line, matches merged #639 P4 slice 2 implementation); branch CI 31378464934 success; pytest 680 green. 3 consecutive distinct-cycle LGTMs (181428, 181650, 182000), no ❌ — merging.