ui: adopt shared status, time, and pluralization standards across CLI commands

[codeaholicguy]

Context

Terminal UI audit after the capacity redesign (commit 3c65af7). Audit covered every command that prints; per-command issues are filed separately. This issue tracks the cross-cutting standards they should converge on.

Problem

The CLI has three incompatible status vocabularies, five date/time formats, and naive pluralization, all implemented per-command:

Command	Status language	Time format
capacity	OK / LIMITED / EXHAUSTED / UNKNOWN (colored)	in 4h 40m · 20:25, Sep 25 · 02:52
status	ready / not ready / fail / info	—
agent list	🟢 run / 🟡 wait / ⚪ idle / ❓ unknown	just now, 5m ago, 2d ago
channel list	enabled / stopped	toLocaleDateString() → 6/4/2026 (machine-locale dependent)
channel status	yes / no	raw ISO → 2026-06-04T19:18:06.962Z
agent detail	role colors	toLocaleTimeString()

Also recurring:

• Naive pluralization: 1 agent(s) waiting, 5 required check(s) failed, 3 location(s).
• Per-value colors implemented by string-matching rendered text (e.g. statusStyle in status/render.ts, the text.includes("run") column style in agent.ts), which is fragile and duplicated in each command.
• JSON output emitted via raw console.log in some commands and ui.text in others.

Expectation

1. One shared status model in packages/cli/src/util/ (e.g. status-styles.ts): a single map of status key → { label, color }, following the STATUS_STYLES pattern introduced in packages/cli/src/commands/capacity/render.ts. All commands map their domain states onto it; nothing colors by parsing rendered strings.
2. One shared time util with: relative past (5m ago), relative future (in 4h 40m · 20:25), absolute (Sep 25 · 02:52), and a now injection parameter for testability (capacity's resetLabel is the reference). No raw ISO and no bare toLocale* in command output.
3. One pluralization helper (pluralize(1, "agent") → "1 agent"), replacing every (s) construction.
4. Document the standard (symbols, colors, date formats) in packages/cli/README.md or docs/, so future commands follow it.

References

• Per-command issues: status, agent, channel, lint, skill, memory, mutating-flow (init/install/setup/phase/docs).
• Precedent: capacity redesign — single per-quota table, shared thresholds, humanized resets.