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/admin.ts

@@ -24,7 +24,7 @@ export function registerAdminCommands(program: Command, context: KtxCliCommandCo
 
   admin
     .command('init')
-    .description('Initialize a Git-backed KTX project directory for maintenance scripts')
+    .description('Initialize a Git-backed ktx project directory for maintenance scripts')
     .argument('[directory]', 'Project directory')
     .option('--force', 'Rewrite ktx.yaml and scaffold files in an existing project', false)
     .action(