fix(#2697): replace retired /gsd: prefix with /gsd- in all user-facing text (#2699)

All workflow, command, reference, template, and tool-output files that
surfaced /gsd:<cmd> as a user-typed slash command have been updated to
use /gsd-<cmd>, matching the Claude Code skill directory name.

Closes #2697

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

get-shit-done/workflows/forensics.md

@@ -207,11 +207,11 @@ Based on the evidence above, the most likely explanation is:
 
 1. {Specific, actionable remediation step}
 2. {Another step if applicable}
-3. {Recovery command if applicable — e.g., `/gsd:resume-work`, `/gsd:execute-phase N`}
+3. {Recovery command if applicable — e.g., `/gsd-resume-work`, `/gsd-execute-phase N`}
 
 ---
 
-*Report generated by `/gsd:forensics`. All paths redacted for portability.*
+*Report generated by `/gsd-forensics`. All paths redacted for portability.*
 ```
 
 **Redaction rules:**