fix(workspace): keep declared group for workspace members in lockfile

[Solaris-star]

Description

Workspace members are always injected as implicit editable dependencies with groups = ["default"]. When a member is only declared in a non-default group (e.g. pdm add -dG test ./subproject), the lockfile still marked it as default (and sometimes both default and test).

Removing the workspace config made groups correct, so the bug is specifically the implicit default injection path.

Fix

1. with_workspace_dependencies(..., exclude=...) — skip members already declared in other groups when injecting into default.
2. _resolve_dependencies — compute declared_elsewhere and pass it as exclude.
3. Resolver find_matches — copy_with(original_req) for workspace candidates so requirement groups follow the declared dependency.

Verification

Minimal workspace repro (pdm add -dG test ./subproject):

# pdm.lock excerpt
[[package]]
name = "subproject"
groups = ["test"]   # no longer includes "default"

Linked Issue

Closes #3816

[frostming]

The tests are failed, please check @Solaris-star

[yangfan-yf-yf]

I reproduced the two CI failures on f01a437 locally on Windows:

py -m uv run pytest tests/cli/test_add.py::test_add_subdirectory_path_updates_workspace tests/test_project.py::test_workspace_member_declared_in_dev_group_not_forced_into_default -q
# 2 failed

The first failure is a regression from can.copy_with(original_req): the workspace candidate used by pdm add packages/foo is no longer editable. The same existing test passes on the current main branch, so the workspace candidate needs to retain its editable requirement while still carrying the declared dependency's group information.

The new test also calls project.get_dependencies(default). That resolves only the default group, so declared_elsewhere never sees the test dependency and the implicit workspace member is expected to be added. Please exercise the all-group lock-resolution path (or otherwise include the declared group in the resolution) when checking the lockfile group result.

[Solaris-star]

Thanks for the precise repro. I pushed ad919d74 with both fixes: the workspace candidate keeps its editable requirement while inheriting only the declared groups, and the regression test now resolves all groups and verifies the final lockfile records foo only in test. I also added the required news fragment. The two focused tests pass locally.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.39%. Comparing base (7cb8367) to head (bd016a3).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3819   +/-   ##
=======================================
  Coverage   86.39%   86.39%           
=======================================
  Files         121      121           
  Lines       13224    13227    +3     
  Branches     2244     2245    +1     
=======================================
+ Hits        11425    11428    +3     
  Misses       1185     1185           
  Partials      614      614           

Flag	Coverage Δ
unittests	86.28% <100.00%> (+<0.01%)	⬆️

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