feat: skill-specific Search Before Building integrations

8 template changes:
- /office-hours: Phase 2.75 Landscape Awareness (WebSearch + three-layer synthesis)
- /plan-eng-review: Step 0 search check with layer provenance annotations
- /investigate: external pattern search + search escalation on hypothesis failure
- /plan-ceo-review: Landscape Check before scope challenge
- /review: search-before-recommending for fix patterns
- /qa-only: WebSearch in allowed-tools
- /design-consultation: three-layer synthesis backport in Phase 2 Step 3
- /retro: eureka moment tracking from ~/.gstack/analytics/eureka.jsonl

All search steps include WebSearch fallback clause.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

design-consultation/SKILL.md

@@ -353,7 +353,12 @@ If browse is not available, rely on WebSearch results and your built-in design k
 
 **Step 3: Synthesize findings**
 
-The goal of research is NOT to copy. It is to get in the ballpark — to understand the visual language users in this category already expect. This gives you the baseline. The interesting design work starts after you have the baseline: deciding where to follow conventions (so the product feels literate) and where to break from them (so the product is memorable).
+**Three-layer synthesis:**
+- **Layer 1 (tried and true):** What design patterns does every product in this category share? These are table stakes — users expect them.
+- **Layer 2 (new and popular):** What are the search results and current design discourse saying? What's trending? What new patterns are emerging?
+- **Layer 3 (first principles):** Given what we know about THIS product's users and positioning — is there a reason the conventional design approach is wrong? Where should we deliberately break from the category norms?
+
+**Eureka check:** If Layer 3 reasoning reveals a genuine design insight — a reason the category's visual language fails THIS product — name it: "EUREKA: Every [category] product does X because they assume [assumption]. But this product's users [evidence] — so we should do Y instead." Log the eureka moment (see preamble).
 
 Summarize conversationally:
 > "I looked at what's out there. Here's the landscape: they converge on [patterns]. Most of them feel [observation — e.g., interchangeable, polished but generic, etc.]. The opportunity to stand out is [gap]. Here's where I'd play it safe and where I'd take a risk..."

design-consultation/SKILL.md.tmpl

@@ -112,7 +112,12 @@ If browse is not available, rely on WebSearch results and your built-in design k
 
 **Step 3: Synthesize findings**
 
-The goal of research is NOT to copy. It is to get in the ballpark — to understand the visual language users in this category already expect. This gives you the baseline. The interesting design work starts after you have the baseline: deciding where to follow conventions (so the product feels literate) and where to break from them (so the product is memorable).
+**Three-layer synthesis:**
+- **Layer 1 (tried and true):** What design patterns does every product in this category share? These are table stakes — users expect them.
+- **Layer 2 (new and popular):** What are the search results and current design discourse saying? What's trending? What new patterns are emerging?
+- **Layer 3 (first principles):** Given what we know about THIS product's users and positioning — is there a reason the conventional design approach is wrong? Where should we deliberately break from the category norms?
+
+**Eureka check:** If Layer 3 reasoning reveals a genuine design insight — a reason the category's visual language fails THIS product — name it: "EUREKA: Every [category] product does X because they assume [assumption]. But this product's users [evidence] — so we should do Y instead." Log the eureka moment (see preamble).
 
 Summarize conversationally:
 > "I looked at what's out there. Here's the landscape: they converge on [patterns]. Most of them feel [observation — e.g., interchangeable, polished but generic, etc.]. The opportunity to stand out is [gap]. Here's where I'd play it safe and where I'd take a risk..."