fix: gstack-slug bash compatibility — source to eval (#354)

* fix: replace source <(gstack-slug) with eval for bash compatibility

Under bash with set -euo pipefail, source <(cmd) process substitution
doesn't reliably set variables in the caller's scope. The variables
stay empty and -u (nounset) crashes the script. eval "$(cmd)" works
correctly in both bash and zsh.

Fixes: gstack-review-read, gstack-review-log, gstack-slug comment,
gen-skill-docs.ts resolver functions, and regression tests.

* chore: bump version and changelog (v0.11.4.0)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

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

design-review/SKILL.md

@@ -774,7 +774,7 @@ Compare screenshots and observations across pages for:
 
 **Project-scoped:**
 ```bash
-source <(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null) && mkdir -p ~/.gstack/projects/$SLUG
+eval "$(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null)" && mkdir -p ~/.gstack/projects/$SLUG
 ```
 Write to: `~/.gstack/projects/{slug}/{user}-{branch}-design-audit-{datetime}.md`
 
@@ -1142,7 +1142,7 @@ Write the report to both local and project-scoped locations:
 
 **Project-scoped:**
 ```bash
-source <(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null) && mkdir -p ~/.gstack/projects/$SLUG
+eval "$(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null)" && mkdir -p ~/.gstack/projects/$SLUG
 ```
 Write to `~/.gstack/projects/{slug}/{user}-{branch}-design-audit-{datetime}.md`
 

design-review/SKILL.md.tmpl

@@ -224,7 +224,7 @@ Write the report to both local and project-scoped locations:
 
 **Project-scoped:**
 ```bash
-source <(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null) && mkdir -p ~/.gstack/projects/$SLUG
+{{SLUG_SETUP}}
 ```
 Write to `~/.gstack/projects/{slug}/{user}-{branch}-design-audit-{datetime}.md`