docs: add Labels section to README and CHANGELOG

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: techjoec

CHANGELOG.md

@@ -7,6 +7,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+**Labels CRUD Commands (GitHub #19, PR #20):**
+- New top-level `labels` command with `list`, `create`, `update`, `delete` subcommands
+- `linear labels list --team ENG` — lists labels with name, color, ID; supports `--output json`
+- `linear labels create "name" --team ENG [--color "#hex"] [--description "text"]`
+- `linear labels update <id> [--name] [--color] [--description]`
+- `linear labels delete <id>`
+- Agent-mode gate: mutations return a clear error when authenticated as an OAuth app actor (Linear workspace restriction)
+- Existing `teams labels` command unchanged
+
 ## [1.4.6] - 2026-01-28
 
 ### Fixed

README.md

@@ -81,6 +81,7 @@ linear auth login
   - [Projects](#projects)
   - [Cycles](#cycles)
   - [Teams](#teams)
+  - [Labels](#labels)
   - [Users](#users)
   - [Claude Code Skills](#claude-code-skills)
 - [Cycle Analytics](#cycle-analytics)
@@ -262,6 +263,7 @@ All commands support both flags:
 - **Cycles**: `list`, `get`, `analyze`
 - **Projects**: `list`, `get`
 - **Teams**: `list`, `get`, `labels`, `states`
+- **Labels**: `list`
 - **Users**: `list`, `get`, `me`
 - **Search**: all search operations
 
@@ -628,6 +630,20 @@ linear teams labels ENG                      # Team labels
 linear teams states ENG                      # Workflow states
 ```
 
+### Labels
+
+```bash
+linear labels list --team ENG               # List all labels (with IDs)
+linear labels list --team ENG --output json  # JSON output
+
+# Create, update, delete (requires user auth, not agent/app)
+linear labels create "needs-review" --team ENG --color "#ff0000" --description "PR needs review"
+linear labels update LABEL-UUID --name "needs-code-review" --color "#ff6600"
+linear labels delete LABEL-UUID
+```
+
+> **Note:** Label mutations (create/update/delete) require user authentication. OAuth app actors cannot manage labels due to Linear workspace permissions. Use `linear auth login` as a user.
+
 ### Users
 
 ```bash