feat(functions): add qc quick-chat wrapper around aichat

Defaults to the bundled 'cli' role (concise, terminal-friendly output),
installed on first use by symlinking scripts/cli-agent.md into the aichat
config dir. Inherits all aichat flags and completions via --wraps; passing
--role/-r forwards unchanged. Only defined when aichat is installed.
--help prepends a banner and rewrites aichat's own help to qc.

Docs: fish-config.md 5.12 + index keywords.

docs/fish-config.index

@@ -150,6 +150,9 @@ devlogs=### agents-init
 claude-cli=### claude
 claude-docs=### claude-docs
 claude-pr=### claude-pr
+qc=### qc
+quick-chat=### qc
+aichat=### qc
 superpowers=### superpowers
 media=## 5.13 Media and Utilities
 dng2avif=### dng2avif