Add v0.6.0: full skill/agent QA pass, 3 new agents tested, template cleanup

Skills fixed: sprint-status (stale escalation, threshold), retrospective
(existing file detection, missing data fallback), changelog (misc category,
task-ref count), patch-notes (BLOCKED on missing changelog, tone/template
paths), story-readiness (Phase 0 mode resolution, QL-STORY-READY gate),
art-bible, brainstorm, design-system, ux-design, dev-story, story-done,
create-architecture, create-control-manifest, map-systems, propagate-design-change,
quick-design, prototype, asset-spec.

Agents fixed: all 4 directors (gate verdict token format), engine-programmer,
ui-programmer, tools-programmer, technical-artist (engine version safety),
gameplay-programmer (ADR compliance), godot-gdextension-specialist (ABI warning),
systems-designer (escalation path to creative-director), accessibility-specialist
(model, tools, WCAG criterion format, findings template), live-ops-designer
(escalation paths, battle pass value language), qa-tester (model, test case
format, evidence routing, ambiguous criteria, regression scope).

Specs updated: smoke-check and adopt specs rewritten to match actual skill
behavior. catalog.yaml reset to blank template state. Removed
session-state marketing research file, removed session-state from gitignore.

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

.claude/agents/godot-gdextension-specialist.md

@@ -273,6 +273,16 @@ macos.release = "res://rust/target/release/lib[name].dylib"
 - Not building for all target platforms in CI (discover issues late)
 - Allocating in hot paths instead of pre-allocating buffers
 
+## ABI Compatibility Warning
+
+GDExtension binaries are **not ABI-compatible across minor Godot versions**. This means:
+- A `.gdextension` binary compiled for Godot 4.3 will NOT work with Godot 4.4 without recompilation
+- Always recompile and re-test extensions when the project upgrades its Godot version
+- Before recommending any extension patterns that touch GDExtension internals, verify the project's
+  current Godot version in `docs/engine-reference/godot/VERSION.md`
+- Flag: "This extension will need recompilation if the Godot version changes. ABI compatibility
+  is not guaranteed across minor versions."
+
 ## Version Awareness
 
 **CRITICAL**: Your training data has a knowledge cutoff. Before suggesting