[CLI] Add hf spaces duplicate command

[davanstrien]

Adds hf spaces duplicate <from_id> [<to_id>] so duplicate sits alongside the other hf spaces lifecycle/management commands (pause, restart, settings, secrets, variables, volumes, card, logs, hardware).

hf spaces duplicate username/my-space
hf spaces duplicate username/my-space my-copy --private
hf spaces duplicate username/my-space my-copy --hardware l4x4 --secrets HF_TOKEN -v hf://buckets/org/b:/data

Design notes

• Wraps duplicate_repo, not duplicate_space — the latter is @_deprecate_method(version="2.0", ...) at hf_api.py:8468. duplicate_repo already plumbs through all the Space-specific args.
• Why a new command when hf repos duplicate --type space exists? Same rationale as hf spaces card ([CLI] Add hf models card and hf datasets card commands #4118): per-type ergonomic wrapper keeps the spaces namespace internally consistent.
• Flag names — --hardware, --sleep-time match hf spaces settings ([CLI] Add --hardware flag to hf spaces settings #4163), not --flavor from hf repos duplicate. Internal-namespace consistency over cross-namespace mirror.
• Flag set is a full mirror of hf repos duplicate minus --type.
• PublicOpt / ProtectedOpt are copy-pasted verbatim from cli/repos.py:77–91. Could be lifted to _cli_utils.py for one source of truth — happy to do that as a small follow-up.
• No tests per [CLI] Add spaces lifecycle commands: pause, restart, sleep #4155 review feedback. No confirmation prompt — duplicate is creation, not destruction.

Hint chain

After a successful duplicate:

Hint: Use `hf spaces info <to_id>` to monitor the runtime stage.
Hint: Source secrets and variables are not copied. Run `hf spaces secrets ls <from_id>`
      and `hf spaces variables ls <from_id>` to see what to set on the new Space.

secrets ls / variables ls already emit hints with the add syntax, so an agent chains through without this command pre-fetching anything.

Smoke test

$ hf spaces duplicate multimodalart/dreambooth-training davanstrien/duplicate-smoke-test --private
# 400: "Hardware must be specified when duplicating a Space"  ← server validation surfaces cleanly

$ hf spaces duplicate multimodalart/dreambooth-training davanstrien/duplicate-smoke-test --private --hardware cpu-basic
# Space duplicated  + hint chain renders correctly

# Carry-over check:
$ hf spaces variables add davanstrien/duplicate-smoke-test -e CARRY_TEST_VAR=hello
$ hf spaces secrets   add davanstrien/duplicate-smoke-test -s CARRY_TEST_SECRET=shh
$ hf spaces duplicate davanstrien/duplicate-smoke-test davanstrien/duplicate-carry-test-2 --private --hardware cpu-basic
$ hf spaces variables ls davanstrien/duplicate-carry-test-2   # → no results
$ hf spaces secrets   ls davanstrien/duplicate-carry-test-2   # → no results
# Confirmed: secrets and variables do not carry over from source.

Found while testing (separate follow-up)

duplicate_repo (hf_api.py:8466) crashes with KeyError: 'url' when exist_ok=True hits a 409 — the swallow path falls through to r.json()["url"] on what's actually an error body. Independent of this PR; will open a separate fix.

---

Note

Medium Risk
Adds a new CLI surface that creates/duplicates Spaces and forwards many runtime/visibility/env options to the Hub API, so mistakes could create misconfigured or incorrectly visible Spaces. Changes are localized to CLI wiring and docs, with no core auth or data-path refactors.

Overview
Adds a new hf spaces duplicate FROM_ID [TO_ID] command that wraps HfApi.duplicate_repo(..., repo_type="space"), supporting visibility flags plus Space runtime overrides like --hardware, --sleep-time, deprecated --storage, and optional secrets/vars/volume mounts.

Updates the CLI guide and generated CLI reference to document the new command and its flags, and prints post-run hints (including that source secrets/variables are not copied).

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[bot-ci-comment]

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[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.14%. Comparing base (1daa48b) to head (20ba280).
⚠️ Report is 327 commits behind head on main.

Files with missing lines	Patch %	Lines
src/huggingface_hub/cli/spaces.py	50.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4197      +/-   ##
==========================================
+ Coverage   75.00%   77.14%   +2.14%     
==========================================
  Files         145      170      +25     
  Lines       13978    19437    +5459     
==========================================
+ Hits        10484    14995    +4511     
- Misses       3494     4442     +948     

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