chore: update .gitignore to exclude local tooling, build artifacts, and internal docs

Remove Claude Code configs, skills, publish artifacts, HTML mockups,
and internal planning docs from git tracking. Files remain local.

.gitignore

@@ -1,13 +1,21 @@
 # Claude Code local config
-.claude/hooks/
-.claude/settings.json
-.claude/settings.local.json
-.claude/subprocess-settings.json
+.claude/
+Client/.claude/
 Server/.claude/
 
-# Research / personal notes
+# Claude Code skills
+skills/
+
+# AI-specific / internal planning docs
 IMPROVEMENTS.md
 STOAT-RESEARCH.md
+PROMPTS.md
+SKILL.md
+AUDIT.md
+LANGUAGE-REVIEW.md
+MIGRATION-PLAN.md
+TESTING-STRATEGY.md
+CLIENT-ARCHITECTURE.md
 docs/superpowers/
 
 # Server runtime artifacts
@@ -16,7 +24,18 @@ Server/config.yaml
 Server/data/
 
 # Test coverage artifacts
+*.out
 Server/cov.out
 Server/cover.out
 Server/coverage.out
 Server/ws_cover.out
+Server/ws_cov.out
+
+# Client build artifacts
+Client/publish/
+Client/publish-single/
+Client/publish-release/
+
+# HTML mockups (large design reference files)
+Client/login-mockup.html
+Client/ui-mockup.html