AX fixes: --json on all commands, exit codes, channel resolution, init

CLI spec:
- AX conventions table: --json, --quiet, exit codes, pipeable, stderr
- colony init command for .colony.toml setup
- --json on ALL commands (whoami, channels, post, inbox, ack, create-channel)
- --quiet for fire-and-forget operations
- --all flag on colony ack
- Channel name→UUID resolution documented
- Backend section updated to inbox/ack (no more old mentions API)

AX skill:
- Added principle #9: Pipeable machine-readable output

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude/skills/ax/SKILL.md

@@ -52,6 +52,7 @@ If `$ARGUMENTS` is provided, focus on relevant surfaces.
 | 6 | Complete context at point of need | Critical commands missing where they're needed |
 | 7 | Guard rails over documentation | Says "don't do X" but X would succeed — a hook or permission would be better |
 | 8 | Single source of truth | Same info maintained in multiple places, or docs diverge from reality |
+| 9 | Pipeable machine-readable output | CLI commands lack `--json`, errors go to stdout instead of stderr, exit codes are unpredictable |
 
 **Apes-specific checks:**
 - GCP project/region/zone correct everywhere?