docs: enrich docs/specs and remove placeholders

**Motivations:**
- Make docs/specs implementation-ready without empty sections or placeholders.

**Root causes:**
- Multiple specs still contained non-actionable placeholders (N/A, “see above”, "..."), and inconsistent “no cache” wording.

**Correctifs:**
- Replace placeholders with explicit tables, structures, and typed examples.
- Align “no cache / no memorization” statements where relevant.

**Evolutions:**
- Add a features doc entry to track the documentation enrichment effort.

**Pages affectées:**
- docs/specs/*
- docs/features/docs-specs-enrichment.md
- docs/leo.md
- docs/plan-enrich-docs-specs.md

docs/specs/inventaire_animaux.md

@@ -111,7 +111,9 @@ function getCollectionBonus(player):
   count = countDistinctSpecies(player.animals)
   if count >= 75: return 0.20
   if count >= 50: return 0.10
-  // ...
+  if count >= 30: return 0.05
+  if count >= 15: return 0.02
+  if count >= 5: return 0.01
   return 0
 ```