Technical Debt: Fix SC2086 and SC2155 ShellCheck warnings

[senomorf]

📋 Issue Description

Address the SC2086 (quote variables) and SC2155 (separate declare/assign) ShellCheck warnings that are currently suppressed globally in .shellcheckrc.

🎯 Background

From PR #43 linting infrastructure review, Claude identified this as low-priority technical debt. These warnings are currently commented out in .shellcheckrc with notes to "fix these individually".

📊 Current State

• SC2086 instances: ~51 across scripts and tests
• SC2155 instances: ~51 across scripts and tests
• Total affected files: ~28 shell scripts

🔧 Tasks

Phase 1: Enable Warnings

• Remove # disable=SC2086 and # disable=SC2155 comments from .shellcheckrc
• Run ShellCheck to get full list of violations

Phase 2: Fix Issues Systematically

• SC2086: Add double quotes around variables to prevent globbing/word splitting
  • Example: $var → "$var"
  • Exception: Cases where word splitting is intentional (add inline # shellcheck disable=SC2086)
• SC2155: Separate declare and assign statements to avoid masking return values
  • Example: local var=$(command) → local var; var=$(command)

Phase 3: Validate

• Run full test suite to ensure no regressions
• Verify all ShellCheck warnings are addressed or properly suppressed

📈 Benefits

• Improved error handling: SC2155 fixes ensure command failures aren't masked
• Better variable safety: SC2086 fixes prevent accidental globbing/word splitting
• Cleaner linting: Reduces global suppressions in favor of targeted fixes

🕒 Estimated Effort

• 2-3 hours spread across multiple sessions
• Risk: Low (quality improvements, not functional changes)

📝 Acceptance Criteria

• SC2086 and SC2155 warnings enabled in .shellcheckrc
• All legitimate violations fixed with proper quoting/declaration patterns
• Intentional cases have inline suppressions with comments
• All tests pass after changes
• ShellCheck reports zero SC2086/SC2155 violations

🏷️ Labels

• technical-debt
• code-quality
• shellcheck
• low-priority