chore: rename project to excalidraw-mcp-sentinel

- Package name: @sanjibdevnath/mcp-excalidraw-local → excalidraw-mcp-sentinel
- GitHub repo: celstnblacc/mcp-excalidraw-local → celstnblacc/excalidraw-mcp-sentinel
- Docker images, CLI binary, CI workflows, docs all updated
- Version reset to 1.0.0 for independent release track
- Added "Why this fork?" section to README
- Removed superseded planning docs (PLAN.md, PLAN_v2.md, REVIEW.md, HANDOFF.md)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/npm-publish.yml

@@ -58,7 +58,7 @@ jobs:
       - name: Check if version exists on NPM
         id: check
         run: |
-          if npm view @sanjibdevnath/mcp-excalidraw-local@${{ steps.version.outputs.version }} version 2>/dev/null; then
+          if npm view excalidraw-mcp-sentinel@${{ steps.version.outputs.version }} version 2>/dev/null; then
             echo "exists=true" >> "$GITHUB_OUTPUT"
           else
             echo "exists=false" >> "$GITHUB_OUTPUT"