refactor: enforce ktx naming and AGENTS.md compliance sweep (#289)

Align the tree with AGENTS.md/CLAUDE.md conventions:

- Rewrite user-facing strings, docs, and tests to lowercase `ktx`
  (no bare uppercase `KTX` tokens remain outside literal identifiers).
- Drop the legacy `historicSql` migration path and its now-unused
  helpers, per the no-backward-compat rule.
- Remove `as unknown as` / `any` casts: narrow `BaseTool` generics to
  `z.ZodObject`, add a typed `createLookerClient`, and delete the dead
  `getParametersSchema`/`toAnthropicFormat` pre-AI-SDK helpers.
- Use `InvalidArgumentError` for Commander parse failures.
- Finish the adapter→connector prose conversion in the `ktx.yaml` docs
  while keeping the literal `adapters` config key.

packages/cli/src/setup-ready-menu.ts

@@ -99,7 +99,7 @@ export async function runKtxSetupReadyChangeMenu(
       { value: 'databases', label: 'Databases' },
       { value: 'sources', label: 'Context sources' },
       ...(status.runtime.required ? [{ value: 'runtime', label: 'Runtime' }] : []),
-      { value: 'context', label: 'Rebuild KTX context' },
+      { value: 'context', label: 'Rebuild ktx context' },
       { value: 'agents', label: 'Agent integration' },
       { value: 'exit', label: 'Exit' },
     ],