fix(skills): valid YAML enums and stored note_type casing in schema examples

Two Codex review fixes in memory-onboarding's schema guide:
- Quote enum field values in the Picoschema YAML example — an unquoted
  flow list with a trailing description is not valid YAML, so copying
  the block produced schema notes that fail to parse.
- Use the stored lower-case note type in schema_validate/schema_diff/
  schema_infer examples: the live API matches Entity.note_type exactly,
  so note_type="Task" would find none of the seed notes written with
  note_type="task".

Signed-off-by: Cody Faust <cody@luminarysol.com>

Author: cfaust990

skills/memory-onboarding/references/schema-guide.md

@@ -68,9 +68,9 @@ Schemas are notes (conventionally in a `Schemas/` folder) whose frontmatter meta
 
 ```yaml
 schema:
-  status(enum): [open, in-progress, blocked, done], current state
+  status(enum): "[open, in-progress, blocked, done], current state"
   due?: string, due date if any (Month D, YYYY)
-  priority?(enum): [low, medium, high], urgency
+  priority?(enum): "[low, medium, high], urgency"
   project?: Project, parent project note
   steps?(array): string, ordered sub-steps
 ```
@@ -120,9 +120,9 @@ Key points:
 
 ## Validation & drift
 
-- `schema_validate(note_type="Task")` — check all notes of a type; also works on a single note. Reports missing required fields, unknown fields, type mismatches, invalid enum values.
-- `schema_diff(note_type="Task")` — finds drift: fields notes use that the schema doesn't define (candidates to add as optional), and schema fields nobody uses (candidates to drop).
-- `schema_infer(note_type="Task")` — when notes of a type already exist without a schema, infer one from their actual structure instead of designing from scratch.
+- `schema_validate(note_type="task")` — check all notes of a type; also works on a single note. Reports missing required fields, unknown fields, type mismatches, invalid enum values.
+- `schema_diff(note_type="task")` — finds drift: fields notes use that the schema doesn't define (candidates to add as optional), and schema fields nobody uses (candidates to drop).
+- `schema_infer(note_type="task")` — when notes of a type already exist without a schema, infer one from their actual structure instead of designing from scratch.
 
 Evolution loop: `schema_diff` → edit the schema note (append changelog row, bump version if breaking) → `schema_validate` → fix outliers. Suggest the user run this monthly-ish once the system has real volume.