docs: document the skills subcommands in the CLI reference

[rajarshidattapy]

Description

Fixes #199

Adds a Skills section to docs/cli-reference.mdx documenting the four skills subcommands and the flags that control skills add.

webcmd skills add is the second command in the README Quick Start, docs/index.mdx, and docs/quickstart.mdx — the install step every new user runs — but the command reference never showed it, or the other three subcommands, or any of their flags.

Everything in the new section is taken from the registrations rather than paraphrased:

Documented	Source
skills list / add / update / remove	src/cli.ts:857, :872, :893, :908
--scope <user|project>	normalizeScope, src/skills.ts:162-165 (global and local are accepted aliases)
--provider <agents|codex|claude>	src/cli.ts:875
Prompts for whichever of scope and harness was not passed	resolveSkillAddOptions, src/cli.ts:96-116
Never prompts outside a TTY or with --json	isInteractiveSkillAdd, src/cli.ts:92-94

That last row is the practically useful one and was not written down anywhere: an agent or CI job running skills add non-interactively needs to know it will not block on a prompt.

Placed between Plugins and External CLIs, since plugins and skills are the two extension surfaces on the page.

Stacking

This branch is based on fix/cli-reference-missing-commands, not on main, because that branch already corrects the skills row in the Top-Level Commands table ("List and read…" → "List, add, update, and remove…"). Branching from main would have touched the same line twice across two PRs.

• Against its base branch, this PR is +13 / -0 — the new section only.
• Against main, it shows +17 / -1, because it carries the base branch's table changes too.

Please merge the base PR first. If you would rather have one self-contained PR, say so and I will rebuild this against main with both changes and close the other.

Related issue:

Type of Change

• 🐛 Bug fix
• ✨ New feature
• 🌐 New site adapter
• 📝 Documentation
• ♻️ Refactor
• 🔧 CI / build / tooling

Checklist

• I ran the checks relevant to this PR
• I updated tests or docs if needed
• I included output or screenshots when useful

Notes on the checklist:

• Docs-only change to one .mdx file; no code, tests, or generated artifacts are touched. Each claim was verified against its registration in src/ rather than by running the suite.
• No automated check covers this page's contents. src/docs-sync-review.ts lists docs/cli-reference.mdx as a watched path only.

Adapter Notes

Not applicable — no adapter is added or modified in this PR.

• Updated generated or lean docs when command discoverability changed
• Used positional args for the command's primary subject unless a named flag is clearly better
• Normalized expected adapter failures to CliError subclasses instead of raw Error

Screenshots / Output

Diff against the base branch — one file, +13:

 Hosted mode supports the same `plugin search` and `plugin install` grammar for Webcmd-verified marketplace adapters. Other plugin management commands remain local-only in hosted mode.

+## Skills
+
+Bundled agent skills ship with the package. `webcmd skills add` links them into an agent harness and is part of first-time setup.
+
+```bash
+webcmd skills list
+webcmd skills add
+webcmd skills update
+webcmd skills remove
+```
+
+On a TTY, `skills add` prompts for whichever of scope and harness you did not pass. Use `--scope <user|project>` and `--provider <agents|codex|claude>` to skip the prompts, or `--path <skills-dir>` to link into a custom directory. Outside a TTY, and with `--json`, it never prompts. Run `skills update` after upgrading the package to refresh the links.
+
 ## External CLIs

[github-actions]

🟢 No documentation gap found — medium confidence

The automated review found no documentation gap in the supplied changes.

This review is advisory and does not block merging.