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-05-train-stat.puml

@@ -0,0 +1,28 @@
+@startuml uc-05-train-stat
+autonumber
+title UC-05 Train Stat (design sequence)
+actor Player
+participant "GymBoundary\n«/api/characters/{id}/gym»" as boundary <<boundary>>
+participant "TrainingService\nsb-core::services::train_stat" as control <<control>>
+participant "ResourceRegenerator\napply_regen" as regen <<entity>>
+participant "TrainingGrounds\nTRAINING_GROUNDS + training_cost" as entity <<entity>>
+
+== Train ==
+Player -> boundary : POST stat name
+boundary -> regen : apply_regen(character)
+regen --> boundary : character (regenerated)
+boundary -> control : train_stat(character, stat)
+control -> entity : cost = training_cost (x1.3 per 10 points)
+alt not enough energy
+  control --> boundary : 422 (DomainError)
+else not enough gold
+  control --> boundary : 422 (DomainError)
+else unknown stat
+  control --> boundary : 400 (DomainError)
+else ok
+  control -> entity : stat +1 (energy -1, gold -cost)
+  control -> entity : constitution: recompute max HP (clamp current)
+  control --> boundary : {success, message, character}
+  boundary --> Player : {success, message, character}
+end
+@enduml