As a developer I want gym-wide shared templates and exercise library so instructors can collaborate on programs and muscle mappings

[ChristopherRotnes]

Summary

Templates (session_templates) and the exercise library (exercise_library) are currently user-private. Co-instructors at the same gym cannot see or edit each other's templates or exercises, forcing duplicate work and inconsistent muscle mappings. Making both gym-wide lets the team build a shared program library and correct muscle data together.

Priority

High

UI spec (Carbon g100)

• Bibliotek "Mine maler" tab renamed to "Maler" (templates are no longer personal)
• Template cards: show "Av [display_name]" in var(--cds-font-mono) 11px below exercise/muscle count — only when the creator differs from the current user
• Exercise rows: same attribution below muscle chips
• No permission gating on Edit/Delete buttons — all co-instructors can act on any item

Data model

RLS changes (migration gym_wide_templates_and_exercises):

-- session_templates: INSERT own, SELECT/UPDATE/DELETE same-gym
-- session_template_exercises: ALL via parent template gym check
-- exercise_library: INSERT own, SELECT/UPDATE/DELETE same-gym

-- Same-gym check pattern (mirrors sessions policy):
EXISTS (
  SELECT 1 FROM user_gyms ug1
  JOIN user_gyms ug2 ON ug2.sporty_business_unit_id = ug1.sporty_business_unit_id
  WHERE ug1.user_id = auth.uid()
    AND ug2.user_id = <table>.user_id
)

user_id retained on both tables as "created by" for attribution display.

fetchTemplates() and fetchLibraryExercises() updated to join profiles!user_id(display_name).

Acceptance criteria

• Co-instructor at same gym can see all templates in Bibliotek
• Co-instructor can edit template name and exercises
• Co-instructor can delete any template or exercise
• Creator attribution shown on items not created by current user
• touchTemplate succeeds when using a colleague's template in Planlegger
• INSERT always uses own user_id (cannot create on behalf of another)
• Existing tests pass (npm test — 82 tests)
• Users without user_gyms entry cannot see templates (covered by ensureGymMembership on sign-in)

Out of scope

• Retroactive muscle remapping when an exercise is edited (tracked separately)
• Private/opt-out templates — all templates are gym-wide with no exceptions
• Cross-gym template sharing

[ChristopherRotnes]

Implemented and shipped in v1.2.8 (merged PR #170). All acceptance criteria met: gym-wide RLS policies, creator attribution, tab rename, touchTemplate on colleague templates. Verified on production.