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/test/context/core/config-reference.test.ts

@@ -4,7 +4,7 @@ import { join } from 'node:path';
 import { describe, expect, it } from 'vitest';
 import { resolveKtxConfigReference, resolveKtxHomePath } from '../../../src/context/core/config-reference.js';
 
-describe('KTX config references', () => {
+describe('ktx config references', () => {
   it('resolves env references without returning empty values', () => {
     expect(resolveKtxConfigReference('env:AI_GATEWAY_API_KEY', { AI_GATEWAY_API_KEY: ' gateway-key ' })).toBe(
       'gateway-key',