openup: doc restructure - template alignment + design sequences (non-PSP)

Align the OpenUP markdown set to the blank templates (process-data repo,
templates/openup/) per BUILD-CHECKLIST 7. Scenario step text unchanged;
the EA model needs no change (brief descriptions already live in the
model's UC/actor notes).

- vision.md: positioning tables, stakeholder summary, user environment,
  needs-and-features table (R1/R2), other product requirements
- use-case-model.md: per-UC specification sections (brief description,
  actor descriptions, named alternative/exception subsections with
  numbered steps, post-conditions, special requirements)
- supplementary-specifications.md: category tables with priority and
  use-case columns + reverse coverage matrix; IDs unchanged
- test/quality-check-procedure.md: migrated from Joplin (single content
  home); stale open items marked resolved (WI-1/WI-2)
- analysis-design/sequences/: 12 PlantUML design sequences (lifelines =
  analysis classes, messages = design elements; per the PlantUML layout
  style guide) + PNG renders; embedded in Architecture Notebook 9.3
- Joplin consolidated: project content notes deleted (all live in
  docs/game + docs/openup); Joplin keeps the status note only

docs/openup/analysis-design/sequences/uc-03-manage-characters.puml

@@ -0,0 +1,31 @@
+@startuml uc-03-manage-characters
+autonumber
+title UC-03 Manage Characters (design sequence)
+actor Player
+participant "CharacterCatalog\n«/api/users/{id}/characters»" as boundary <<boundary>>
+participant "CharacterFactory\nsb-core::character::create_character" as control <<control>>
+participant "Character\nsb-shared::character" as entity <<entity>>
+participant "ResourceRegenerator\napply_regen" as regen <<entity>>
+
+== Create ==
+Player -> boundary : POST name, race, class (user id)
+boundary -> control : create_character(rng, user, name, race, class)
+alt user missing
+  control --> boundary : 404
+else name invalid
+  control --> boundary : 400
+else valid
+  control -> entity : roll stats (d6+5 +- race mods)
+  control -> entity : max HP/energy/nerve from class
+  control -> entity : gold 50 + level-1 spells (casters)
+  control -> entity : assign next character id, persist
+  control --> boundary : character
+  boundary --> Player : character (full)
+end
+
+== List / View ==
+Player -> boundary : GET characters (own; admin: any)
+boundary -> regen : apply_regen(character)
+regen --> boundary : character (regenerated)
+boundary --> Player : characters (regen applied)
+@enduml