Make shellcheck happy

[mkysel]

Fix shell script variable quoting to satisfy shellcheck linting requirements

Adds double quotes around variable references in shell scripts to prevent word splitting and globbing issues, and renames the GitHub workflow from spellcheck to shellcheck. The changes affect multiple shell scripts:

• Renames .github/workflows/lint-spellcheck.yml to lint-shellcheck.yml and updates workflow name and job name
• Adds quotes around variable references in dev/cmd/register-local-node-1 for NODE_ADDRESS, PRIVATE_KEY, XMTPD_SIGNER_PUBLIC_KEY, and NODE_ID variables
• Adds quotes around variable references in dev/cmd/register-local-node-2 for the same variables
• Adds quotes around profile variable references in dev/docker/down and dev/docker/up scripts

📍Where to Start

Start with the renamed GitHub workflow file .github/workflows/lint-shellcheck.yml to understand the change from spellcheck to shellcheck linting.

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Macroscope summarized ae13aac.

[graphite-app]

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