[CLI] Make --format human override agent auto-detection

[hanouticelina]

Related to #4860.

Summary

• When a registered harness is detected, auto resolves to agent. Passing --format human restored the layout but not the rest: progress bars were disabled once at import and never re-enabled, and ANSI called is_agent() directly so colors stayed off.
• set_mode() now derives everything from the resolved mode: progress bars on for human, off otherwise (unless HF_HUB_DISABLE_PROGRESS_BARS is set, which keeps priority), and it tells ANSI whether colors are on.
• ANSI.set_enabled() is the new toggle. Callers outside the hf CLI (login flow, tiny-agents CLI) don't set it and fall back to is_agent() as before. NO_COLOR still wins.
• Side effect: colors are now off in json and quiet too, not only agent. Seems right for machine-oriented modes.
• User-agent attribution and hf env are unchanged and keep using detect_agent().

Example

In a pty with TERM_PROGRAM=WarpTerminal, which is detected as the warp harness:

Before, --format human gave the human layout but no progress bar and no colors:

$ hf download sentence-transformers/all-MiniLM-L6-v2 onnx/model_qint8_arm64.onnx --local-dir /tmp/x --format human
✓ Downloaded
  path: /tmp/x/onnx/model_qint8_arm64.onnx

After:

$ hf download sentence-transformers/all-MiniLM-L6-v2 onnx/model_qint8_arm64.onnx --local-dir /tmp/x --format human
onnx/model_qint8_arm64.onnx: reconstructing file: 100% 23.0M/23.0M [00:01<00:00, 14.5MB/s]
✓ Downloaded   <- green
  path: /tmp/x/onnx/model_qint8_arm64.onnx

Without --format, the same command still resolves to agent mode (path=..., no bars).

---

Note

Low Risk
CLI presentation only; respects existing env overrides and preserves non-CLI ANSI behavior via is_agent() fallback.

Overview
--format human now fully overrides agent harness detection for terminal UX, not just layout.

Output.set_mode() ties ANSI colors and progress bars to the resolved format: human turns both on; agent, json, and quiet turn colors off and progress bars off unless HF_HUB_DISABLE_PROGRESS_BARS is already set (env still wins).

ANSI gains set_enabled() and an internal override so the hf CLI drives coloring from output mode; other callers keep the previous is_agent() fallback. NO_COLOR is unchanged and still disables styling.

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[bot-ci-comment]

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[hanouticelina]

✅

[Wauplin]

Nice fix, thanks you! Pre-approving with a nit :)