feat(examples): rewrite baker-family as coherent Competition Week narrative

Rewrote the baker-family example around a unified story: the annual Harvest
Baking Competition is Saturday. Martha's sourdough starter Old Maggie is
sluggish from a cold snap, Jane is secretly entering the FreeStyle category,
Emma's science fair project is "The Chemistry of Fermentation", Henry is
judging for the first time and worried about impartiality, and Roland is
defending last year's title.

The week's schedules (Mon guild meeting → Tue test bakes → Wed sourcing →
Thu dough prep → Fri science fair → Sat competition → Sun recovery) are
now fully populated with narrative-specific actions.

Files split for composability:
- behaviors/baker_behaviors.sb → 5 focused files by character/domain
- schema/types.sb → 4 files (core, baking, world, social)
- schedules/work_schedules.sb → 4 files (one per schedule)
- relationships/baker_family_relationships.sb → family + bakery

Strong typing: replaced all enumerable string fields with concepts
(BakerSpecialty, Occupation, LocationType, InstitutionType, ParentingStyle,
Intensity, BakeryDomain, BakingDiscipline, ManagementDomain,
CompetitiveAdvantage).

Remove new-syntax-demo.sb (superseded by baker-family example).

examples/baker-family/characters/emma.sb

@@ -20,17 +20,24 @@ character Emma from Child {
     mood: 0.85
 
     ---backstory
-    Emma is the bright, energetic daughter of Martha and Jane. She loves
-    helping in the bakery on weekends, though she's not allowed to work
-    the ovens yet. She's fascinated by the chemistry of baking and often
-    asks her mothers endless questions about why dough rises, how yeast
-    works, and what makes bread crusty.
+    Emma is the bright, energetic daughter of Martha and Jane. She is
+    fascinated by the chemistry of baking — why dough rises, how yeast
+    works, what makes bread crusty — and has turned that curiosity into
+    her school science fair project: "The Chemistry of Fermentation."
 
-    At school, she excels in science and math, and dreams of one day
-    creating her own innovative recipes. She learns the science of bread
-    from Martha and the art of decoration from Jane. For now, she's
-    content to help package goods and chat with the regular customers
-    who've watched her grow up.
+    She borrowed a microscope from the school lab and has been studying
+    Old Maggie under magnification, sketching the yeast colonies and
+    tracking how temperature affects their activity. Her poster board
+    is covered in hand-drawn diagrams of lactobacillus and graphs of
+    rise times at different temperatures. The science fair is Friday
+    evening, and she has been rehearsing her presentation to anyone
+    who will listen — Henry, the regular customers, even Roland once
+    when he stopped by to buy flour.
+
+    On weekends she helps in the bakery, packaging goods and chatting
+    with customers. She is not allowed to work the ovens yet, but she
+    knows the recipes by heart. She is quietly proud that her science
+    project connects her two worlds: school and the bakery.
     ---
 }