feat: add wrapper script to auto-mount local_folder sources

[mrsimpson]

Problem

When running the Docker container, every local_folder source in config.yaml must be manually added as a -v flag in the docker run command. The config and the Docker command are two sources of truth that must stay in sync.

Example today:

docker run -i \
  -v ~/project/.knowledge:/knowledge/.knowledge \
  -v ~/project/docs:/knowledge/docs:ro \
  -v ~/project/wiki:/knowledge/wiki:ro \
  agentic-knowledge-mcp

With config.yaml:

docsets:
  - id: docs
    sources:
      - type: local_folder
        paths:
          - ./docs
  - id: wiki
    sources:
      - type: local_folder
        paths:
          - ./wiki

Proposed solution

A wrapper script (e.g., run.sh) that:

1. Parses config.yaml for local_folder source paths (using js-yaml, already a dependency)
2. Resolves relative paths against the config directory
3. Generates the docker run command with -v flags for each path
4. Mounts .knowledge as writable, all source dirs as read-only

./run.sh                          # runs with all docsets
./run.sh my-docs                  # runs only a specific docset

The script could also:

• Validate all paths exist before invoking Docker (instant feedback)
• Accept extra -v flags for anything the config does not cover
• Accept environment variables for proxy config on corporate networks

Acceptance criteria

• Script reads config.yaml and extracts all local_folder paths
• Relative paths are resolved against the config directory
• Script generates correct docker run with volume mounts
• All source paths validated before Docker invocation
• Usage documented in docs/docker.md's open points