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/commands/sql-commands.ts

@@ -26,7 +26,7 @@ export function registerSqlCommands(program: Command, context: KtxCliCommandCont
     .command('sql')
     .description('Execute parser-validated read-only SQL against a configured connection')
     .argument('<sql...>', 'SQL query to execute')
-    .requiredOption('-c, --connection <id>', 'KTX connection id')
+    .requiredOption('-c, --connection <id>', 'ktx connection id')
     .option('--max-rows <n>', 'Maximum rows to return', parseSqlMaxRowsOption, DEFAULT_MAX_ROWS)
     .addOption(
       new Option('--output <mode>', 'Output mode: pretty (default), plain (TSV), or json').choices([