refactor: remove teams support and harden tests

[AlexanderNZ]

This is the bigger cleanup pass: I split the server into focused tool modules and made the tests easier to run for real orgs.

What I changed

• replaced the monolithic entrypoint with a tool registry and src/index.ts
• removed teams support from the API surface
• added a hardened IcePanel client (timeouts, retries, clearer errors)
• added integration tests and CLI parsing tests
• removed hardcoded test values and documented required env vars
• ignored .pnpm-store/ to avoid accidental staging

Why I did it

• the old file was hard to maintain and extend
• tests needed a real, repeatable setup instead of baked-in defaults
• teams support was unused and added noise to the API surface

Test plan

• not run

Recommended merge order

• PR refactor: reduce filter param duplication #19 (filter refactor)
• PR feat: add HTTP transport (Streamable HTTP) #20 (HTTP transport)
• PR feat: add Docker support #21 (Docker support)
• PR feat: add IcePanel write tools #22 (write tools)
• PR refactor: remove teams support and harden tests #23 (refactor + tests)
• PR feat: add tag and tag group reads #24 (tags + tag groups)
• PR feat: add domain reads #25 (domains)
• PR feat: add connection reads #26 (connections)
• PR feat: add diagram reads #27 (diagrams)
• PR feat: add flow reads #28 (flows)
• PR feat: add model object export reads #29 (model object exports)
• PR docs: expand read tools and tests #30 (docs + tests)