feat(cli): let ktx setup --agents choose an install directory (#298)

Split the fused directory concept into projectDir (what the agent config
references) and installRoot (where project-scoped files are written), so
users can install .claude/, .mcp.json, skills, and rules where they open
their agent instead of only in the ktx project directory.

- Add --install-dir <path> (resolved against cwd, created if missing,
  mutually exclusive with --global/--local, rejected for claude-desktop).
- Add an interactive directory menu: ktx project dir / Current directory
  (hidden when it equals the project dir) / Custom directory… / Global
  scope (shown only when every target supports it).
- Expand a leading ~ in typed/quoted paths so the ~/… menu hints round-trip.
- Record installRoot in the install manifest and merge key; thread it
  through file planning, MCP config paths, summaries, and next actions.
- Refresh uv.lock to 0.12.0 for the editable ktx-sl and ktx-daemon packages.

docs-site/content/docs/cli-reference/ktx-setup.mdx

@@ -29,6 +29,7 @@ below.
 | `--agents` | Install agent configuration and rules only | `false` |
 | `--target <target>` | Agent target: `claude-code`, `claude-desktop`, `codex`, `cursor`, `opencode`, or `universal` | - |
 | `--global` | Install agent integration into the global target scope for `claude-code` or `codex` | `false` |
+| `--install-dir <path>` | Directory to install project-scoped agent config into. Defaults to the ktx project directory; resolved against the current directory and created if missing. Use it to install `.claude/`, `.mcp.json`, and rules where you open your agent (e.g. `--install-dir .`). Mutually exclusive with `--global` and `--local` | ktx project dir |
 | `--yes` | Accept project creation and runtime install defaults where setup asks for confirmation | `false` |
 | `--no-input` | Disable interactive terminal input | - |