fix(cli): honor NO_COLOR, add --no-color, disable colors when stdout is not a TTY (#1281)

[maxmilian]

Fixes #1281

Problem

Human-format output (query, status, callers, callees, impact, files, …) embedded ANSI color codes unconditionally: piping to a file or another tool captured the escapes, and the standard escape hatch (https://no-color.org) was ignored — NO_COLOR=1 produced byte-identical output. For agent/tooling consumers the escapes are wasted bytes and transcript noise, and the workaround (--json) is ~5× the bytes of the human format.

Fix

All CLI coloring already flows through the colors palette in src/bin/codegraph.ts (plus a mini-palette in src/upgrade/index.ts), so the fix is one shared gate — colorEnabled() in a new src/ui/colors.ts:

1. --no-color anywhere on the command line disables color — it's stripped from argv before commander parses (same pre-parse intercept pattern as -v), so it also works after subcommands (codegraph query foo --no-color) where commander would otherwise reject it as an unknown option; still registered on the program so it shows in --help
2. a non-empty NO_COLOR environment variable disables color (an empty NO_COLOR does not, per the spec)
3. otherwise color renders only when stdout is a TTY — piped/redirected output is escape-free by default

With color disabled the palette collapses to empty strings, so every existing colors.X interpolation and chalk.X() helper becomes a plain-text no-op — no call sites change.

Verification

• New __tests__/cli-no-color.test.ts (5 tests, end-to-end against the built binary, red before / green after): piped query/status/callers output must be escape-free; NO_COLOR=1 honored; --no-color accepted after a subcommand; empty NO_COLOR does not disable color
• Full suite: 142 files / 2405 passed (npm run build && npm test)
• TTY regression check: under a pseudo-TTY (script -q /dev/null …), query output still renders colors; --help lists the new flag
• CHANGELOG entry under [Unreleased] → Fixes

Notes

• src/ui/shimmer-worker.ts (index progress animation) still writes ANSI cursor control when piped — that's a rendering concern distinct from command output and untouched here; happy to follow up separately if wanted.

🤖 Generated with Claude Code

https://claude.ai/code/session_01XWwajmLbgJbK6JBCY8nKfk