chore: remove outdated morphir-elm subtree and related Elm code (#425)

* chore: restructure skills directory layout

Move skill definitions from single files to directory structure:
- morphir-developer.md -> morphir-developer/SKILL.md
- release-manager.md -> release-manager/SKILL.md
- Remove skills.json (no longer needed)

* chore: remove outdated morphir-elm subtree and related Elm code

Remove legacy Elm code that is no longer needed for the Go implementation:

1. morphir-elm/ - Outdated git subtree of finos/morphir-elm causing:
   - Renovate flagging vulnerability issues in stale npm dependencies
   - 16MB of unused code not relevant to the Go implementation
   - Confusion about which code is authoritative

2. src/Morphir/ - Elm source code for defunct morphir-elm-compiler package

3. packages/morphir-elm-compiler/ - Incomplete TypeScript/Elm hybrid
   compiler package that is not actively maintained

The following are intentionally kept:
- tests/bdd/testdata/morphir-elm/ - Test fixtures fetched from canonical repo

References to finos/morphir-elm in docs/comments remain as they point
to the canonical repository which is the authoritative source.

Closes: morphir-d3g

* fix: correct beads issue prefix to 'morphir'

Author: DamianReeves

.beads/config.yaml

@@ -1 +1 @@
-issue-prefix: "morphir-go"
+issue-prefix: "morphir"

.claude/skills/morphir-developer.md .claude/skills/morphir-developer/SKILL.md.claude/skills/morphir-developer.md renamed to .claude/skills/morphir-developer/SKILL.md

@@ -1,3 +1,8 @@
+---
+name: morphir-developer
+description: Helps with Morphir Go development including workspace setup, go.work management, branch/worktree handling, TDD/BDD workflow, and pre-commit checks. Use when setting up development environment or working on Morphir code.
+---
+
 # Morphir Developer Skill
 
 You are a specialized assistant for developing the Morphir project. You help developers with:

.claude/skills/release-manager.md .claude/skills/release-manager/SKILL.md.claude/skills/release-manager.md renamed to .claude/skills/release-manager/SKILL.md

@@ -1,3 +1,8 @@
+---
+name: release-manager
+description: Manages Morphir releases including changelog updates, version bumping, module tagging, and release execution. Use when preparing or executing a release.
+---
+
 # Release Manager Skill
 
 You are a release manager for the Morphir project. Your role is to help maintainers prepare and execute releases, including changelog management, version bumping, and module tagging.