chore: remove gpg signing skill

.claude/skills/gpg-commit-signing/SKILL.md

@@ -1,43 +0,0 @@
----
-name: gpg-commit-signing
-description: Sign git commits with GPG in non-interactive environments. Use when committing code and the `GPG_PRIVATE_KEY_PASSPHRASE` environment variable is available. Triggers on "commit", "sign commit", "GPG", "git commit -S", or any git operation requiring signed commits.
----
-
-# GPG Commit Signing
-
-Sign commits in headless/non-interactive environments where `/dev/tty` is unavailable.
-
-## Workflow
-
-1. Check whether `GPG_PRIVATE_KEY_PASSPHRASE` is set:
-
-   ```bash
-   test -n "$GPG_PRIVATE_KEY_PASSPHRASE" && echo "available" || echo "not set"
-   ```
-
-   If not set, skip signing — commit without `-S`.
-
-2. Try a direct signed commit first — the environment may already have loopback pinentry configured:
-
-   ```bash
-   git commit -S -m "message"
-   ```
-
-   If this succeeds, no further steps are needed.
-
-3. If step 2 fails with a `/dev/tty` error, use `--pinentry-mode loopback` via a wrapper script:
-
-   ```bash
-   printf '#!/bin/sh\ngpg --batch --pinentry-mode loopback --passphrase "$GPG_PRIVATE_KEY_PASSPHRASE" "$@"\n' > /tmp/gpg-sign.sh
-   chmod +x /tmp/gpg-sign.sh
-   git -c gpg.program=/tmp/gpg-sign.sh commit -S -m "message"
-   rm /tmp/gpg-sign.sh
-   ```
-
-   This passes the passphrase directly to gpg on each signing invocation, bypassing the need for a configured gpg-agent.
-
-## Anti-patterns
-
-- Do not echo or log `GPG_PRIVATE_KEY_PASSPHRASE`.
-- Do not commit without `-S` when the passphrase is available — the project expects signed commits.
-- Do not leave wrapper scripts on disk after committing.