#139 feat: make --skill the default for install; add --skill none to opt out

[Anonymous]

Originally created by: kumaakh

Problem

Every install example in the docs ends with `--skill`. Users and agents copy-paste it without knowing what it means, and the FAQ has a question explaining it. Multiple users have asked why they need to specify it every time if everyone needs it.

The current mental model is: `install` = bare server, `install --skill` = full setup. But in practice nobody wants the bare server.

Proposed change

Introduce a named skill set argument so users can precisely control what gets installed. Default to `all` so bare `install` gives the full experience.

Command	Installs
`apra-fleet install`	MCP server + fleet skill + PM skill (default = `all`)
`apra-fleet install --skill all`	Same as above
`apra-fleet install --skill pm`	MCP server + fleet skill + PM skill
`apra-fleet install --skill fleet`	MCP server + fleet skill only (no PM)
`apra-fleet install --skill none`	MCP server only, no skills
`apra-fleet install --no-skill`	Same as `--skill none`

Skill hierarchy: PM depends on fleet — installing `pm` always includes `fleet`. Installing `fleet` alone gives the raw tools without the PM orchestration layer.

Impact on docs

Once this ships, every install example simplifies:

Before:
```bash
curl -fsSL .../apra-fleet-darwin-arm64 -o apra-fleet && chmod +x apra-fleet && ./apra-fleet install --skill
```

After:
```bash
curl -fsSL .../apra-fleet-darwin-arm64 -o apra-fleet && chmod +x apra-fleet && ./apra-fleet install
```

Files to update: `README.md`, `docs/user-guide.md`, `docs/FAQ.md`, `skills/pm/deploy.md`.

The "Omit `--skill` if you only need basic fleet operations" note in the user guide can be replaced with a brief mention of `--skill none` / `--no-skill` for minimal installs.

Acceptance criteria

• [ ] `apra-fleet install` (no flags) installs MCP + fleet + PM skill
• [ ] `apra-fleet install --skill all` behaves identically
• [ ] `apra-fleet install --skill pm` installs MCP + fleet + PM skill
• [ ] `apra-fleet install --skill fleet` installs MCP + fleet skill only
• [ ] `apra-fleet install --skill none` installs MCP only
• [ ] `apra-fleet install --no-skill` installs MCP only
• [ ] Old `apra-fleet install --skill` (bare flag, no value) treated as `--skill all` for backwards compat
• [ ] `apra-fleet install --help` reflects new defaults and options
• [ ] README, user-guide, FAQ, deploy.md updated to drop `--skill` from examples

[Anonymous]

Originally posted by: kumaakh

When this ships, also complete [#136] — the user guide needs a visible explainer of what install does and what each --skill option installs.

[Anonymous]

Ticket changed by: kumaakh

• status: open --> closed