chore: remove legacy @mosaicstack/cli package

The @mosaicstack/cli package was consolidated into @mosaicstack/mosaic in
a prior refactor, and was already excluded from pnpm-workspace.yaml. This
commit deletes the now-dead packages/cli directory and updates the last
remaining docs references that still pointed at it.

- Delete packages/cli/ (48 files, ~6.6K lines of dead code)
- pnpm-workspace.yaml: drop the !packages/cli exclusion
- tools/install.sh: update install step label
- AGENTS.md, CLAUDE.md: update package map
- README.md, docs/guides/user-guide.md, packages/mosaic/framework/defaults/README.md: update install docs

Verified clean: typecheck, lint, format:check, test (38/38 tasks).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

README.md

@@ -12,10 +12,10 @@ bash <(curl -fsSL https://git.mosaicstack.dev/mosaic/mosaic-stack/raw/branch/mai
 
 This installs both components:
 
-| Component            | What                                                  | Where                |
-| -------------------- | ----------------------------------------------------- | -------------------- |
-| **Framework**        | Bash launcher, guides, runtime configs, tools, skills | `~/.config/mosaic/`  |
-| **@mosaicstack/cli** | TUI, gateway client, wizard, auto-updater             | `~/.npm-global/bin/` |
+| Component               | What                                                             | Where                |
+| ----------------------- | ---------------------------------------------------------------- | -------------------- |
+| **Framework**           | Bash launcher, guides, runtime configs, tools, skills            | `~/.config/mosaic/`  |
+| **@mosaicstack/mosaic** | Unified `mosaic` CLI — TUI, gateway client, wizard, auto-updater | `~/.npm-global/bin/` |
 
 After install, set up your agent identity:
 
@@ -26,7 +26,7 @@ mosaic init          # Interactive wizard
 ### Requirements
 
 - Node.js ≥ 20
-- npm (for global @mosaicstack/cli install)
+- npm (for global @mosaicstack/mosaic install)
 - One or more runtimes: [Claude Code](https://docs.anthropic.com/en/docs/claude-code), [Codex](https://github.com/openai/codex), [OpenCode](https://opencode.ai), or [Pi](https://github.com/mariozechner/pi-coding-agent)
 
 ## Usage