fix: actually wire STDIO attach for docker-image MCP servers

Commit 1bd5087 added attachInteractive to the orchestrator interface
but never hooked it up in mcp-proxy-service — sendViaPersistentAttach
was promised in the commit message but missing from the diff. Servers
with a distroless image whose entrypoint IS the MCP server (gitea-mcp)
ended up needing a bogus `command: [node, dist/index.js]` workaround
that silently failed on every exec, leaving clients with empty tool
lists.

Changes:
- PersistentStdioClient: take a StdioMode discriminated union. Exec
  mode runs a command via execInteractive; attach mode talks to PID 1
  via attachInteractive.
- mcp-proxy-service: dispatch by config — command → exec; packageName
  → exec via runtime runner; dockerImage-only → attach. Error
  serialization no longer drops non-Error objects as "[object Object]".
- templates/gitea.yaml: remove the command workaround; the image CMD
  runs as PID 1 and mcpd attaches.
- Add unit tests covering both modes and the unsupported-orchestrator
  paths.

Also required (separate repo): mcpd's k8s Role needed pods/attach
added alongside pods/exec; updated in kubernetes-deployment/…/mcpctl/server.ts
and kubectl-patched on the live cluster.

Verified end-to-end against mcpctl.ad.itaz.eu:
- gitea (attach): 49 tools listed, real tools/call round-trip.
- aws-docs (exec via packageName): 4 tools, no regression.
- docmost (exec via command): 11 tools, no regression.
- mcpd suite: 634/634 passing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

templates/gitea.yaml

@@ -4,12 +4,10 @@ description: Gitea MCP server for repositories, issues, PRs, and code management
 dockerImage: "docker.gitea.com/gitea-mcp-server:latest"
 transport: STDIO
 repositoryUrl: https://gitea.com/gitea/gitea-mcp
-command:
-  - /app/gitea-mcp
-  - -t
-  - stdio
-# Health check disabled: STDIO health probe requires packageName (npm-based servers).
-# This server uses a custom dockerImage. Probe support for dockerImage STDIO servers is TODO.
+# No command: the image's entrypoint IS the MCP server. mcpd attaches to PID 1
+# stdin/stdout (attach mode) rather than exec-ing a new process. The image is
+# distroless and has no node/shell, so exec-based STDIO would fail.
+# Health check disabled: STDIO health probe requires node in the container.
 env:
   - name: GITEA_HOST
     description: Gitea instance URL (e.g. https://gitea.example.com)