Corrección: feat(install): project capabilities into a directory target (#353) #357

Source PR: #353
Branch: feat/issue-341-install-dir
Head reviewed: 942b415

Push the fixes to the branch above; do not open a new pull request. Comment on the PR and on this issue when done.

Blocking findings

• parseTargetDir silently ignores every argument after --target-dir (internal/cli/install.go:96): The for loop body returns unconditionally on its first iteration, so only args[1] is ever inspected. Any argument appearing after a consumed --target-dir value is dropped without a diagnostic, while a non-flag first argument is refused with invalid_command. This contradicts the fail-closed argument handling the same stack adds for doctor and uninstall (runUninstallCommand/runDoctorCommand reject every unknown argument with invalid_command).
  • Failure scenario: User runs cortex install --target-dir /a --target-dir /b (or appends any extra token after the value). The command exits 0 and projects the catalog into /a; /b is silently ignored with no diagnostic, so capabilities land in a directory the user did not ask for, with no error to notice.
• Claims "Fixes feat: project capabilities to a user-selected directory target on install #341" but defers the QA-actor half of that issue's scope (internal/cli/install.go:140): Issue feat: project capabilities to a user-selected directory target on install #341 scope: "cortex install --target-dir projects skills and QA actors as plain SKILL.md files into the chosen directory" and acceptance criterion: "Install into an empty target directory writes the full capability set with a manifest that records provenance and hashes." The buildDirectoryRequests comment states the opposite: "skill-only (QA actors render as skills in feat: render QA actors as skills for directory targets and document the consumption contract #344, not here)", yet the PR body says "Fixes feat: project capabilities to a user-selected directory target on install #341". The criterion is unsatisfied at the head that claims to close the issue.
  • Failure scenario: Run cortex install --target-dir <empty dir> at this head: skills are projected but QA actors are not (they are deferred to feat: render QA actors as skills for directory targets and document the consumption contract #344/feat(qa): project QA actors as skills for directory targets and document the mode #356), so the directory does not contain the full capability set that issue feat: project capabilities to a user-selected directory target on install #341's acceptance criterion requires, while the PR is marked as fixing it.

Acceptance criteria

• Fixed: parseTargetDir silently ignores every argument after --target-dir (internal/cli/install.go:96). The scenario below no longer reproduces: User runs cortex install --target-dir /a --target-dir /b (or appends any extra token after the value). The command exits 0 and projects the catalog into /a; /b is silently ignored with no diagnostic, so capabilities land in a directory the user did not ask for, with no error to notice.
• Fixed: Claims "Fixes feat: project capabilities to a user-selected directory target on install #341" but defers the QA-actor half of that issue's scope (internal/cli/install.go:140). The scenario below no longer reproduces: Run cortex install --target-dir <empty dir> at this head: skills are projected but QA actors are not (they are deferred to feat: render QA actors as skills for directory targets and document the consumption contract #344/feat(qa): project QA actors as skills for directory targets and document the mode #356), so the directory does not contain the full capability set that issue feat: project capabilities to a user-selected directory target on install #341's acceptance criterion requires, while the PR is marked as fixing it.