dot generator add/list/remove

[mathieusouflis]

Problem statement

Developers who want to use a custom generator with dot have no way to register it without modifying the dot source code. There is no CLI to manage local generators.

Proposed solution

Implement dot generator add/list/remove in cmd/dot/cmd_generator.go.

dot generator add ./my-generator    # register a local generator path
dot generator list                  # list registered generators: name, language, modules, source
dot generator remove my-generator   # unregister by name

Local generators are stored in .dot/generators.json:

{
  "generators": [
    { "name": "my-generator", "source": "./my-generator", "version": "local" }
  ]
}

At startup, buildRegistry() reads .dot/generators.json and loads registered generators in addition to the official ones.

Alternatives considered

Require users to fork dot and add generators to cmd/dot/build.go. Current workaround but not scalable.
Subprocess-based loading. Better long-term but requires the loading mechanism decision first.

Area

Core

Additional context

Depends on: Community generator loading mechanism decision (open-decisions.md #1).