fix(init): reject empty/whitespace project names

[nadav-y]

Summary

apm.yml can end up with an empty name field (name: ''), written by
apm itself rather than by a user typo. Once that happens, every later
apm install / apm lock / apm compile on that manifest hard-fails
with:

Failed to parse apm.yml: Invalid apm.yml identity: 'name' must be a non-empty string

with no way to recover short of hand-editing the file.

Root cause

#2155 tightened APMPackage.from_apm_yml's identity validation: name
and version must now be non-empty strings, not just present keys. That
check itself is correct and intentional. What's missing is upstream of
it: nothing guaranteed a valid name before apm.yml was written to
disk in the first place, so two pre-existing, unrelated code paths could
silently produce name: '':

1. apm install <pkg> auto-bootstrap (commands/install.py) — when no
   apm.yml exists, the project name is derived from Path.cwd().name
   (or Path.home().name for -g/global installs). That's '' at a
   filesystem/drive root. Concretely: a container image with no WORKDIR
   set (Docker's default WORKDIR is /) running
   apm install <pkg> --target claude writes name: '' straight into the
   auto-created apm.yml. This is the confirmed trigger for the reported
   bug — verified end-to-end by reproducing an empty Path.cwd().name.

2. apm init interactive prompt — rich.Prompt.ask() only substitutes
   the default when the raw input is exactly "". Typing a single space
   at the "Project name" prompt returns " " (not the default), which the
   caller then .strip()s to "" before validation. The old
   _validate_project_name only rejected path separators and '..', not
   emptiness, so this also silently wrote name: ''. Separately verified
   and reproduced; not what caused the reported issue, but the same class
   of bug through a different entry point.

Fix

• _validate_project_name now rejects empty/whitespace-only names (in
  addition to the existing path-separator/'..' checks).
• New _resolve_bootstrap_project_name() helper, used by the install.py
  auto-bootstrap path, falls back to "my-project" (matching the existing
  placeholder convention in commands/deps/cli.py) when the derived
  candidate is invalid.
• Updated the apm init interactive-prompt and CLI-arg error messages to
  mention emptiness, not just path separators.

Test plan

• tests/unit/test_init_command.py: new unit tests for
  _validate_project_name (empty/whitespace) and
  _resolve_bootstrap_project_name (fallback + passthrough), plus an
  integration test that a blank/whitespace apm init prompt re-prompts
  instead of writing name: ''.
• Manually reproduced both trigger paths against an unpatched checkout
  and confirmed the fix resolves both.
• ruff check / ruff format --check clean on all touched files.
• Full test_init_command.py + test_install_command.py suites pass
  (174 tests).

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR tightens project-name handling so apm init and the apm install <pkg> auto-bootstrap path no longer create apm.yml manifests with an empty/whitespace name, aligning upstream behavior with the stricter identity validation introduced in #2155.

Changes:

• Reject empty/whitespace project names in _validate_project_name.
• Add _resolve_bootstrap_project_name() and use it in install auto-bootstrap to fall back to "my-project" when Path.cwd().name (or Path.home().name) is empty/invalid.
• Update apm init error messages and add unit/integration tests covering the new validation and interactive re-prompt behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
tests/unit/test_init_command.py	Adds unit tests for empty/whitespace name validation and bootstrap-name fallback, plus an interactive re-prompt regression test.
src/apm_cli/commands/install.py	Routes auto-bootstrap project naming through _resolve_bootstrap_project_name() before writing apm.yml.
src/apm_cli/commands/init.py	Updates CLI + interactive error messages to mention non-empty requirement.
src/apm_cli/commands/_helpers.py	Extends _validate_project_name to reject empty/whitespace; introduces _resolve_bootstrap_project_name().