refactor(routing): rename local/claude to fast/thinking model pair

The routing decision is about reasoning capacity, not cost or provider.
Fast model (koala/qwen35-9b-fast) handles high-pass-rate calls; thinking
model (iguana/gemma4-26b) handles low-pass-rate calls. Removes the
implicit Anthropic dependency from the routing pod — both models go
through LiteLLM.

Renames: HYPERGUILD_LOCAL_MODEL → HYPERGUILD_FAST_MODEL,
HYPERGUILD_CLAUDE_MODEL → HYPERGUILD_THINKING_MODEL,
Router.LocalModel → FastModel, Router.ClaudeModel → ThinkingModel,
log decision "claude_fallback" → "thinking_fallback".

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

internal/routing/router.go

@@ -24,8 +24,8 @@ type Router struct {
 	Fetcher     *Fetcher
 	Logger      *Logger
 	Policy      Policy
-	LocalModel  string
-	ClaudeModel string
+	FastModel     string
+	ThinkingModel string
 	Complete    CompleteFunc
 }
 
@@ -40,9 +40,9 @@ func (r *Router) Run(ctx context.Context, in RunInput) (string, int64, error) {
 	hash := CanonicalHash(in.System, in.User)
 	decision := r.Policy.Decide(pr, hash)
 
-	model := r.ClaudeModel
+	model := r.ThinkingModel
 	if decision == DecideLocal {
-		model = r.LocalModel
+		model = r.FastModel
 	}
 
 	out, ms, err := r.Complete(ctx, model, in.System, in.User)
@@ -59,13 +59,13 @@ func (r *Router) Run(ctx context.Context, in RunInput) (string, int64, error) {
 	}
 
 	if err != nil && decision == DecideLocal {
-		slog.Warn("router: local failed, falling open to claude", "skill", in.Skill, "err", err)
-		out, ms, err = r.Complete(ctx, r.ClaudeModel, in.System, in.User)
+		slog.Warn("router: fast failed, falling open to thinking model", "skill", in.Skill, "err", err)
+		out, ms, err = r.Complete(ctx, r.ThinkingModel, in.System, in.User)
 		if lerr := r.Logger.LogDecision(ctx, LogEntry{
 			SessionID:   in.SessionID,
 			Skill:       in.Skill,
-			Decision:    "claude_fallback",
-			Message:     fmt.Sprintf("model=%s, after-local-error", r.ClaudeModel),
+			Decision:    "thinking_fallback",
+			Message:     fmt.Sprintf("model=%s, after-fast-error", r.ThinkingModel),
 			ProjectRoot: in.ProjectRoot,
 			DurationMs:  ms,
 			Failed:      err != nil,