feat(node): add TypeScript sibling project for npm-based install

Introduces @kuns/claude-mailbox under node/, a wire-compatible TypeScript
port of the .NET daemon that distributes via the public Gitea npm registry.
The .NET project stays in src/ClaudeMailbox/ untouched; users pick whichever
flavor they prefer.

- node/ project: fastify + @modelcontextprotocol/sdk StreamableHTTPServerTransport
  + better-sqlite3, schema and wire surface match the C# version (port 47822,
  X-Mailbox header, MCP tool names, snake_case SQLite columns)
- Cross-platform autostart: Scheduled Task (Win, no admin) / Windows Service
  (Win, --service) / launchd (mac) / systemd --user (linux)
- 9/9 vitest tests pass; end-to-end /health + send/check round-trip verified
- CI split: existing ci.yml/release.yml renamed to *-dotnet.yml with path
  filters, new ci-node.yml and release-node.yml publish to Gitea npm registry
- install.ps1 / install.sh bootstrap one-liners at repo root; homebrew/
  contains a tap formula template
- README install section reordered: npm path primary, dotnet publish secondary

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci-dotnet.yml

@@ -0,0 +1,45 @@
+name: CI (.NET)
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "src/**"
+      - "tests/**"
+      - "ClaudeMailbox.slnx"
+      - "global.json"
+      - ".gitea/workflows/ci-dotnet.yml"
+  pull_request:
+    branches:
+      - main
+    paths:
+      - "src/**"
+      - "tests/**"
+      - "ClaudeMailbox.slnx"
+      - "global.json"
+      - ".gitea/workflows/ci-dotnet.yml"
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    env:
+      DOTNET_ROOT: /home/mika/.dotnet
+    steps:
+      - name: Checkout
+        uses: https://github.com/actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Build
+        run: |
+          set -euo pipefail
+          export PATH="$DOTNET_ROOT:$PATH"
+          dotnet build tests/ClaudeMailbox.Tests/ClaudeMailbox.Tests.csproj -c Release
+
+      - name: Test
+        run: |
+          set -euo pipefail
+          export PATH="$DOTNET_ROOT:$PATH"
+          dotnet test tests/ClaudeMailbox.Tests/ClaudeMailbox.Tests.csproj \
+            -c Release --no-build --logger "console;verbosity=normal"