docs: session handoff 64 + ADR-0047 implemented (#22/#24)

Flip ADR-0047 Status -> implemented (commits f879d54..2d0f4b2, phased
A->B->C + flat-rectangle restyle); update the README index entry to
match (implemented, flat black-on-yellow rectangles, final 2290-green
tally, website-cast follow-up noted). Add session handoff 64 covering
#24 (vi load-picker nav) and #22 (ADR-0047 demo overlay layer).

docs/adr/0047-demonstration-overlay-layer.md

@@ -2,13 +2,38 @@
 
 ## Status
 
-Accepted (2026-06-10). Addresses Gitea **#22**. Builds the in-app
+Accepted (2026-06-10); **implemented 2026-06-11**, phased A→B→C (closes
+Gitea **#22**). Addresses Gitea **#22**. Builds the in-app
 overlay/annotation primitive that screencast recording (ADR-website-001
 §2, the `autocast` pipeline) and a future guided-lesson system both
 need. Adjacent to ADR-0046 (the nav-mode sidebar overlay it must
 coexist with) and unblocks the polished version of the assistive-editor
 and projects (`#24`) casts.
 
+**Implementation (commits `f879d54` → `2d0f4b2`).** Phase A
+(`f879d54`): `--demo` flag + `RDBMS_PLAYGROUND_DEMO` env →
+`App.demo_mode`, mirroring the `--no-undo` plumbing; help text mentions
+only the visible badges (the `Ctrl+]` caption trigger stays
+low-profile, D6). Phase B (`2584e76`): automatic keystroke badges — pure
+`demo_badge_label`, set in `App::update` before the modal gate, expired
+by a ~1.5 s runtime timer via the new `nearest_deadline` helper that
+extends the time-boxed-`recv` arm condition **without** regressing the
+ADR-0027 indicator debounce (the rewrite tracks `Instant` deadlines;
+verified equivalent). Phase C (`241f60c`): the stealth `Ctrl+]`
+caption buffer in `App::update`, intercepted before the modal gate so
+captions work over the load picker. Post-build (`2d0f4b2`, user
+decision): the overlays render as **flat filled yellow rectangles** (no
+border glyphs, one-cell text margin) to read as a distinct callout. A
+whole-implementation `/runda` pass returned **PASS** with no blockers;
+the only untested wiring is the `run_loop` badge timer (not unit-testable
+in isolation — same posture as the existing `IndicatorDebounce`; the
+pure pieces are all tested). One intentional, user-acknowledged
+behaviour: `Ctrl-C` is inert while capturing (every non-`Ctrl+]` key is,
+by spec; exit capture with `Ctrl+]`). Tests: 2290 passing / 0 failing /
+0 skipped (Tier-1 label fn + caption FSM + `nearest_deadline`, Tier-2
+dark/light/stacked/wrapped/clamp snapshots + black-on-yellow style,
+CLI parse/env); clippy clean.
+
 All primary forks and the visual placement were **user-confirmed** —
 including the two follow-ups settled after the first draft: the trigger
 key (**`Ctrl+]`**, the maximally-obscure valid single-byte code, over