fix: use consistent allowed-tools YAML format (#179)

Convert inline array format to list format in discuss-phase.md
to match all other command files in the codebase.

Before: allowed-tools: [Read, Write, Bash, ...]
After:  allowed-tools:
          - Read
          - Write
          - Bash
          ...

commands/gsd/discuss-phase.md

@@ -2,7 +2,13 @@
 name: gsd:discuss-phase
 description: Gather phase context through adaptive questioning before planning
 argument-hint: "<phase>"
-allowed-tools: [Read, Write, Bash, Glob, Grep, AskUserQuestion]
+allowed-tools:
+  - Read
+  - Write
+  - Bash
+  - Glob
+  - Grep
+  - AskUserQuestion
 ---
 
 <objective>