Extract mcp-server to its own repo (meshtastic/meshtastic-mcp) (#10861)

The Python MCP server + hardware test harness that lived under mcp-server/
now has its own home at https://github.com/meshtastic/meshtastic-mcp
(published, versioned independently). Remove the in-tree copy and wire the
firmware repo to the standalone server externally.

- Delete mcp-server/ (96 files) and the 8 harness-coupled AI workflow files
  under .claude/commands/ and .github/prompts/ that drove ./mcp-server/
  run-tests.sh — those workflows now ship with meshtastic-mcp as skills.
- .mcp.json: register the server via
  `uvx --from git+https://github.com/meshtastic/meshtastic-mcp meshtastic-mcp`
  instead of a local ./mcp-server/.venv, keeping MESHTASTIC_FIRMWARE_ROOT="."
  so the MCP tools still work from this checkout with no local build.
- Repoint the remaining references (AGENTS.md, CLAUDE.md,
  .github/copilot-instructions.md, bin/regen-*.sh, docs, Screen.h,
  userPrefs.jsonc, test/fixtures/nodedb/README.md, .trunk/configs/.bandit)
  at the standalone repo. The MCP tool surface is unchanged — only the
  pytest harness moves out; run it from a meshtastic-mcp checkout with
  MESHTASTIC_FIRMWARE_ROOT pointed here.

No build/CI/platformio coupling existed, so nothing in the firmware build
changes.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

.mcp.json

@@ -1,8 +1,12 @@
 {
   "mcpServers": {
     "meshtastic": {
-      "command": "./mcp-server/.venv/bin/python",
-      "args": ["-m", "meshtastic_mcp"],
+      "command": "uvx",
+      "args": [
+        "--from",
+        "git+https://github.com/meshtastic/meshtastic-mcp",
+        "meshtastic-mcp"
+      ],
       "env": {
         "MESHTASTIC_FIRMWARE_ROOT": "."
       }