Add build/serve MCP tools

[amishne]

New MCP experimental tools:

• "build" tool: A new MCP tool that allows for one-off, non-watched builds of Angular projects, similar to
  ng build.
• "serve" tools: A group of new MCP tools to manage the development server:
  • "start_devserver": Starts the Angular development server as a background process.
  • "stop_devserver": Stops a running development server.
  • "wait_for_devserver_build": Waits for a build to complete and reports the logs.

Notes:

• Implementation mostly follows the design doc for build/serve/test workflow.
• The currently-alive devservers are stored as part of the MCP context, and so are maintained across tool invocations.
• Build progress detection relies on hardcoding expected strings to match - see "dev-server.ts".
• Beyond the unit tests, also tested manually in Gemini CLI.
• A bunch of tools, included these new ones, just return basic unweighted structured content, so added a utility function in a "utils.ts" file for that functionality.

[dgp1130]

Thanks for putting this together @amishne! Hopefully my comments should be internally consistent, but there might be a few which you addressed in later commits.

I know I left a lot of feedback, feel free to ack and ignore any comments you don't agree with or would rather follow up on separately from this PR. We definitely don't need to expand the scope any more than it already is.

I think probably my most important concern is just about whether we can reduce the dependency on specific log output and hopefully make this a little more durable to internal changes there.

[dgp1130]

Question: @clydin, I'm curious to know what you think a good timeout would be here. I wonder if 30s might be too short such that some larger projects will hit this 100% of the time and the AI might not know to configure it.

[amishne]

Waiting for feedback from @clydin but changing to 3 minutes for now.