feat: add spine-shelves, adapt spine-books for shelf nesting

sample-books.org

@@ -1,6 +1,7 @@
-#+TODO: WANT(w) READING(r) | READ(d) ABANDONED(a)
+#+TITLE: Spine
 
-* WANT The Left Hand of Darkness
+* Fiction
+** WANT The Left Hand of Darkness
 :PROPERTIES:
 :AUTHOR:  Ursula K. Le Guin
 :ISBN:    978-0441478125
@@ -14,7 +15,7 @@
 :ID:      9a2b-lhd
 :END:
 
-* WANT Dune
+** WANT Dune
 :PROPERTIES:
 :AUTHOR:  Frank Herbert
 :ISBN:    978-0441172719
@@ -28,7 +29,7 @@
 :ID:      7f3c-dun
 :END:
 
-* WANT Piranesi :fiction:
+** WANT Piranesi                                                               :fiction:
 :PROPERTIES:
 :AUTHOR:  Susanna Clarke
 :ISBN:    
@@ -42,7 +43,7 @@
 :ID:      5e8d-pir
 :END:
 
-* READING Use of Weapons                                                          :scifi:literary:
+** READING Use of Weapons                                                      :scifi:literary:
 :PROPERTIES:
 :AUTHOR:  Iain M. Banks
 :ISBN:    978-0316029193
@@ -55,14 +56,15 @@
 :LAST_MODIFIED: [2026-03-09]
 :ID:      8c1e-uow
 :END:
-:LOGBOOK:
+::LOGBOOK:
 - State "READING" from "WANT" [2026-03-01]
-:END:
+::END:
 - [2026-03-02] The two-track structure is doing something I can't name yet.
 - [2026-03-07] Zakalwe's competence reads as a wound.
 - [2026-03-09] The chapter numbering. Oh.
 
-* READ Ancillary Justice :scifi:
+* Science Fiction
+** READ Ancillary Justice                                                    :scifi:
 :PROPERTIES:
 :AUTHOR:  Ann Leckie
 :ISBN:    978-0316246620
@@ -75,10 +77,19 @@
 :LAST_MODIFIED: [2025-11-15]
 :ID:      3a1b-aj
 :END:
-:LOGBOOK:
+::LOGBOOK:
 - State "READ" from "READING" [2026-01-10]
 - State "READING" from "WANT" [2025-11-20]
-:END:
+::END:
 - [2025-11-22] The pronoun game is a genuinely fresh take on identity.
 - [2025-12-05] Justice of Toren's multi-body perspective is unsettling.
 - [2026-01-08] The tea set. Perfect ending.
+
+* Non-Fiction
+** The Checklist Manifesto
+:PROPERTIES:
+:AUTHOR:  Atul Gawande
+:ID:      b2c1-tcm
+:ADDED:   [2026-06-15]
+:LAST_MODIFIED: [2026-06-15]
+:END: