chore: migrate to start-sdk 2.0

[helix-nine]

start-sdk 2.0 migration

Migrates this package to @start9labs/start-sdk 2.0 (requires StartOS 0.4.0-beta.10).

Changes

• SDK pin → 2.0.1, TypeScript → ^6, tsconfig.json extends the shipped tsconfig.base.json, Makefile includes the SDK's s9pk.mk (vendored copy removed), reusable CI workflows repointed to Start9Labs/start-technologies.
• 2.0 API migrations as applicable: sdk.serviceInterface.* → sdk.host.* resolved over the LXC bridge, lazy SubContainer, alerts manifest field removed, and other ### Changed / ### Removed items from the SDK 2.0 changelog.
• Downstream revision bump with release notes; package docs brought onto the current packaging-guide convention.

Test plan

• CI build is green (npm ci → tsc → SDK lint → ncc → s9pk pack).
• Install the built .s9pk on a StartOS 0.4.0-beta.10 server.
• Start the service; confirm it reaches its health check and primary interface.
• For dependents: confirm it connects to its dependency over the LXC bridge.

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