refactor(3597): extract captureConsole + toPosixPath to helpers; dedup makeTmp wrappers; CLAUDE.md MemPalace

## Helper deduplication (16 files)

Two genuinely-duplicated test helpers extracted to tests/helpers.cjs:

- captureConsole(fn) → {stdout, stderr} with ANSI strip + exception
  re-throw after console restore (preserves the #2775 CR contract).
  Removed from 6 bug-N test files (bug-2775, bug-2829, bug-3033,
  bug-3211, bug-3231, bug-3359) where the implementation was either
  byte-identical or trivially-different. installer-migration-install-
  integration's captureConsole has a different signature ({value,
  output}) and stays as-is.

- toPosixPath(p) → p with path.sep → '/'. Returns input unchanged if
  null/undefined for safe optional-chain composition. Replaces the
  local normalizePath in bug-3491-nested-git-worktree (the
  prune-orphaned-worktrees inline normalizeSlashes was already swapped
  for canonicalPath in the cluster-J batch).

## makeTmp/mkScratch wrappers (8 files)

Reduced each local wrapper from a 3-line fs.mkdtempSync(path.join(
os.tmpdir(), ...)) block to a 1-line arrow delegating to
createTempDir (already in helpers.cjs). Bug-number prefix conventions
stay local for readability:

  - bug-2256, bug-2794, feat-3023, feat-3024 → `gsd-<bug>-${prefix}-`
  - bug-3288 → makeTmpDir = createTempDir (identity)
  - bug-3571 → 'gsd-3571-' (no parameter)
  - feat-3595 → mkScratch = `fs-fault-${name}-`
  - project-root-generator → 'gsd-parity-'

bug-3288 also collapsed local rmTmpDir into `cleanup` from helpers
(removes a separate inline rmSync site).

## CLAUDE.md — MemPalace protocol

Adds explicit instruction to call mempalace_status at session start
and mempalace_search / mempalace_kg_query before answering questions
about people, past work, or prior decisions in this project.

## Why this is a real consolidation

Initial survey suggested the bug-N test files could be parameterized
into one install-end-to-end.test.cjs — that turned out to oversell the
savings (~200 LOC on 2238) and to bury per-bug fixture context in a
table. The genuinely duplicated surface was the helpers themselves:
captureConsole copy-pasted ~6×, makeTmp variant copy-pasted ~8×.
Extracting them retires ~170 LOC of pure copy-paste without changing
any test semantics.

Validated: holodeck (ubuntu docker) 11232/0 pass; ratchet guard
still 7/7 at baseline.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/helpers.cjs

@@ -175,4 +175,52 @@ function isUsageOutput(text) {
   return /Usage:\s*gsd-tools/.test(text) && /Commands:/.test(text);
 }
 
-module.exports = { runGsdTools, createTempDir, createTempProject, createTempGitProject, cleanup, parseFrontmatter, isUsageOutput, TOOLS_PATH };
+/**
+ * Run `fn` with console.log/warn/error captured, returning {stdout, stderr}
+ * with ANSI colors stripped. Re-throws any exception fn threw AFTER restoring
+ * the real console so the caller's assertion path sees the failure (without
+ * this, a fn that crashes before printing would falsely pass !hasReady-style
+ * assertions). #2775 CR follow-up established this exact contract.
+ *
+ * Previously duplicated in bug-2775, bug-2829, bug-3033, bug-3211, bug-3231,
+ * bug-3359, and installer-migration-install-integration.
+ */
+function captureConsole(fn) {
+  const stdout = [];
+  const stderr = [];
+  const origLog = console.log;
+  const origWarn = console.warn;
+  const origError = console.error;
+  console.log = (...a) => stdout.push(a.join(' '));
+  console.warn = (...a) => stderr.push(a.join(' '));
+  console.error = (...a) => stderr.push(a.join(' '));
+  let threw = null;
+  try {
+    fn();
+  } catch (e) {
+    threw = e;
+  } finally {
+    console.log = origLog;
+    console.warn = origWarn;
+    console.error = origError;
+  }
+  if (threw) throw threw;
+  const strip = (s) => s.replace(/\x1b\[[0-9;]*m/g, '');
+  return {
+    stdout: stdout.map(strip).join('\n'),
+    stderr: stderr.map(strip).join('\n'),
+  };
+}
+
+/**
+ * Normalize platform path separators to POSIX forward slashes. Use for
+ * cross-platform path comparisons in test assertions where the runtime
+ * emits the platform-native separator (\ on Windows) but the test
+ * fixture or expected literal is POSIX. Returns the input unchanged if
+ * null/undefined so it composes safely with optional chaining.
+ */
+function toPosixPath(p) {
+  return p == null ? p : p.split(path.sep).join('/');
+}
+
+module.exports = { runGsdTools, createTempDir, createTempProject, createTempGitProject, cleanup, parseFrontmatter, isUsageOutput, captureConsole, toPosixPath, TOOLS_PATH };