chore: reorganize examples and templates into examples/ by type (#54)

- Move example skills to examples/skills/
- Move scaffolding templates to examples/{agents,hands,channels,plugins,providers,integrations,skills}/
- Remove legacy skill.toml from example skills; SKILL.md is the canonical format
- Delete top-level templates/ directory

examples/channels/channel.toml

@@ -0,0 +1,10 @@
+id = ""
+name = ""
+description = ""
+category = ""    # one of: messaging, social, enterprise, developer, iot, email
+icon = ""
+protocol = ""    # one of: bot-api, webhook, websocket, rest-api, imap, xmpp, irc, mqtt, matrix
+
+[metadata]
+url = ""
+docs = ""