refactor: remove dead contributor mode, replace with operational self-improvement slot

Contributor mode never fired in 18 days of heavy use (required manual opt-in
via gstack-config, gated behind _CONTRIB=true, wrote disconnected markdown).

Removes: generateContributorMode(), _CONTRIB bash var, 2 E2E tests, touchfile
entry, doc references. Cleans up skip-lists in plan-ceo-review, autoplan,
review resolver, and document-release templates.

The operational self-improvement system (next commit) replaces this slot with
automatic learning capture that requires no opt-in.

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

scripts/resolvers/preamble.ts

@@ -33,7 +33,6 @@ mkdir -p ~/.gstack/sessions
 touch ~/.gstack/sessions/"$PPID"
 _SESSIONS=$(find ~/.gstack/sessions -mmin -120 -type f 2>/dev/null | wc -l | tr -d ' ')
 find ~/.gstack/sessions -mmin +120 -type f -delete 2>/dev/null || true
-_CONTRIB=$(${ctx.paths.binDir}/gstack-config get gstack_contributor 2>/dev/null || true)
 _PROACTIVE=$(${ctx.paths.binDir}/gstack-config get proactive 2>/dev/null || echo "true")
 _PROACTIVE_PROMPTED=$([ -f ~/.gstack/.proactive-prompted ] && echo "yes" || echo "no")
 _BRANCH=$(git branch --show-current 2>/dev/null || echo "unknown")
@@ -323,26 +322,6 @@ jq -n --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" --arg skill "SKILL_NAME" --arg b
 \`\`\``;
 }
 
-function generateContributorMode(): string {
-  return `## Contributor Mode
-
-If \`_CONTRIB\` is \`true\`: you are in **contributor mode**. At the end of each major workflow step, rate your gstack experience 0-10. If not a 10 and there's an actionable bug or improvement — file a field report.
-
-**File only:** gstack tooling bugs where the input was reasonable but gstack failed. **Skip:** user app bugs, network errors, auth failures on user's site.
-
-**To file:** write \`~/.gstack/contributor-logs/{slug}.md\`:
-\`\`\`
-# {Title}
-**What I tried:** {action} | **What happened:** {result} | **Rating:** {0-10}
-## Repro
-1. {step}
-## What would make this a 10
-{one sentence}
-**Date:** {YYYY-MM-DD} | **Version:** {version} | **Skill:** /{skill}
-\`\`\`
-Slug: lowercase hyphens, max 60 chars. Skip if exists. Max 3/session. File inline, don't stop.`;
-}
-
 function generateCompletionStatus(): string {
   return `## Completion Status Protocol
 
@@ -499,7 +478,7 @@ Avoid filler, throat-clearing, generic optimism, founder cosplay, and unsupporte
 
 // Preamble Composition (tier → sections)
 // ─────────────────────────────────────────────
-// T1: core + upgrade + lake + telemetry + voice(trimmed) + contributor + completion
+// T1: core + upgrade + lake + telemetry + voice(trimmed) + completion
 // T2: T1 + voice(full) + ask + completeness
 // T3: T2 + repo-mode + search
 // T4: (same as T3 — TEST_FAILURE_TRIAGE is a separate {{}} placeholder, not preamble)
@@ -523,7 +502,6 @@ export function generatePreamble(ctx: TemplateContext): string {
     generateVoiceDirective(tier),
     ...(tier >= 2 ? [generateAskUserFormat(ctx), generateCompletenessSection()] : []),
     ...(tier >= 3 ? [generateRepoModeSection(), generateSearchBeforeBuildingSection(ctx)] : []),
-    generateContributorMode(),
     generateCompletionStatus(),
   ];
   return sections.join('\n\n');

scripts/resolvers/review.ts

@@ -240,7 +240,6 @@ Follow it inline, **skipping these sections** (already handled by the parent ski
 - AskUserQuestion Format
 - Completeness Principle — Boil the Lake
 - Search Before Building
-- Contributor Mode
 - Completion Status Protocol
 - Telemetry (run last)