feat(cli): smart defaults and flatter command surface for ktx (#177)

Bare invocations now do the obvious thing instead of erroring out, and mode-as-subcommand patterns collapse into flags on the parent. No new top-level commands.

- `ktx ingest` (bare) ingests every configured connection. The `text` subcommand is gone; capture inline notes with `ktx ingest --text "..."` and files with `ktx ingest --file path` (use `-` for stdin). `--text`/`--file` reject a positional connection id; pass `--connection-id` to tag captured notes.
- `ktx connection` (bare) lists; `ktx connection test` (bare) tests every configured connection.
- `ktx wiki` and `ktx sl` flatten `list`/`search`: bare lists, with a `[query...]` positional searches (multi-word joined with spaces). `sl validate` and `sl query` stay as distinct verbs and now read `--connection-id` from the parent.
- `ktx mcp` (bare) prints daemon status.

Adds a shared `resolveConnectionSelection` helper consumed by ingest and connection test. Updates README, docs-site cli-reference and guides, next-steps strings, agent SKILL templates, and all affected tests. Per-package type-check, unit tests (605), smoke tests, and dead-code checks all pass.

packages/cli/src/sl.ts

@@ -197,7 +197,7 @@ export async function runKtxSl(args: KtxSlArgs, io: KtxSlIo = process, deps: Ktx
       await printSlSources({
         rows: sources,
         emptyMessage: `No semantic-layer sources matched "${args.query}" in ${project.projectDir}`,
-        emptyHint: 'Run `ktx sl list` to inspect available sources.',
+        emptyHint: 'Run `ktx sl` to inspect available sources.',
         command: 'sl search',
         output: args.output,
         json: args.json,