fix(deps): drop platformdirs, which is never imported

[fer1994]

Problem

platformdirs is declared as a runtime dependency in pyproject.toml and in the PEP 723 header of src/specify_cli/__init__.py, but nothing in the repository imports it.

$ grep -rn "import platformdirs\|from platformdirs\|platformdirs\." src tests scripts templates extensions presets
(no matches)

The only two occurrences in the whole tree are the two declarations themselves. There is no dynamic import either — nothing reaches it through importlib.import_module or __import__.

Every user who installs specify-cli pulls a package the CLI never touches.

Evidence

Verified by actually removing it rather than by reading alone. After uv sync --extra test:

$ uv run python -c "import importlib.util; print(importlib.util.find_spec('platformdirs') is not None)"
False

With the package genuinely absent from the interpreter:

• specify --help, specify check, specify --version — all work
• Full suite — 8176 passed, 208 skipped, identical to main

Run on macOS 15 (arm64), CPython 3.13.15, against a2c1843.

Scope

Three files, six deleted lines:

• removes the dependency from pyproject.toml
• removes it from the PEP 723 header so the two declarations stay in agreement
• regenerates .github/security-audit-requirements.txt with the command CONTRIBUTING.md documents:

uv pip compile pyproject.toml --extra test --universal --generate-hashes --quiet --no-header --output-file .github/security-audit-requirements.txt

Regenerated without --upgrade deliberately, so the diff is only the four platformdirs lines rather than an unrelated bump of every pinned package.

AI disclosure

Found and written with Claude Code (Opus 5). The claim was verified empirically rather than by inspection alone — the package was removed from the environment and the CLI and full suite were run against its absence. I reviewed the change and re-validated it against current main before opening this.