feat(project): Project.llmProvider semantically names an Llm resource

Why: Phases 0-3 built the server-managed Llm registry; this phase pivots the
existing Project.llmProvider column from "local provider hint" to "named Llm
reference" so operators can pick a centralised Llm per project. No schema
change — the column stays a free-form string for backward compat.

- `mcpctl create project --llm <name>` (+ `--llm-model <override>`) sets
  llmProvider/llmModel to a centralised Llm reference, or 'none' to disable.
- `mcpctl describe project` fetches the Llm catalogue alongside prompts and
  flags values that don't resolve with a visible warning. 'none' is treated
  as an explicit disable, not an orphan.
- `apply -f` doc comments updated; --llm-provider still accepted but now
  documented as naming an Llm resource.
- New `resolveProjectLlmReference(mcpdClient, name)` helper in mcplocal's
  discovery: returns `registered`/`disabled`/`unregistered`/`unreachable`.
  The HTTP-mode proxy-model pipeline will consume this when it pivots to
  mcpd's /api/v1/llms/:name/infer proxy.
- project-mcp-endpoint.ts cache-namespace path gets a comment explaining
  the new resolution order — behavior unchanged, just clarified.

Tests: 6 resolver unit tests + 3 new describe-warning cases. Full suite
1853/1853 (+9 from Phase 3's 1844). TypeScript clean; completions
regenerated for the new create-project flags.

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

completions/mcpctl.bash

@@ -191,7 +191,7 @@ _mcpctl() {
             COMPREPLY=($(compgen -W "--type --description --default --url --namespace --mount --path-prefix --token-secret --config --force -h --help" -- "$cur"))
             ;;
           project)
-            COMPREPLY=($(compgen -W "-d --description --proxy-model --prompt --gated --no-gated --server --force -h --help" -- "$cur"))
+            COMPREPLY=($(compgen -W "-d --description --proxy-model --prompt --llm --llm-model --gated --no-gated --server --force -h --help" -- "$cur"))
             ;;
           user)
             COMPREPLY=($(compgen -W "--password --name --force -h --help" -- "$cur"))