chore(#597): replace count-based ratchet guards with AST lint + named-set allowlists (#603)

The windows-test-parity ratchet greps test source for fs.rmSync-without-
maxRetries (and six other Windows-portability anti-patterns), failing when an
integer offender COUNT exceeds a frozen baseline (rmSync: 95). A count ratchet
is a Goodhart metric: fixing one offender and adding another keeps the count
constant, so a new defect slips through green. Replace it — and every other
count ratchet in the repo — with a layered, masking-proof design.

Behavioral seam test
- tests/helpers-cleanup.test.cjs proves helpers.cleanup() carries the Windows
  EBUSY retry budget. cleanup() delegates retries to Node's fs.rmSync via
  maxRetries (it owns no loop), so the test asserts the option contract
  (recursive/force/maxRetries>0/retryDelay>0) + real-FS removal + the cwd-guard,
  rather than a loop that does not exist. The EBUSY risk is now tested ONCE at
  the helper, not approximated textually at every call site.

Write-time ESLint rule (AST-accurate, replaces the grep)
- eslint-rules/no-raw-rmsync-in-tests.cjs (error in tests/**/*.test.cjs) bans
  raw fs.rmSync, steering to cleanup(). Catches member, computed (fs['rmSync']),
  destructured and aliased forms; escape hatch is inline
  `// eslint-disable-next-line local/no-raw-rmsync-in-tests -- <reason>` only.
- Migrated 336 raw fs.rmSync teardown calls across ~116 test files to cleanup().
  ~18 genuinely load-bearing sites (mid-test SUT/fault-injection removals,
  error-swallowing or name-colliding local teardown helpers) keep the raw call
  with an inline eslint-disable + reason.

Shared anti-ratchet primitive
- scripts/lib/allowlist-ratchet.cjs:
  - assertWithinAllowlist: fails on NOVEL ids (new offender introduced) AND on
    STALE ids (a known offender was fixed but not pruned) — identity, not count,
    and a ratchet DOWN toward zero.
  - assertTightCeiling: a size/length budget whose ceiling must stay within a
    grace band of the high-water mark, so budgets may only tighten, never creep.

Ratchets converted onto the primitive
- windows-test-parity-guard.test.cjs: rmSync rule deleted (now ESLint-enforced);
  the remaining six patterns moved from integer baselines to named-set
  allowlists with ratchet-down.
- scripts/lint-test-file-count.{cjs,allowlist.json}: per-module integer counts →
  named filename sets (closes the swap-a-file-keep-the-count blind spot); a
  module dropping under cap now FAILS to force pruning its allowlist entry.
- enh-2790 skill-count `<= 63` → named skill allowlist (ratchets toward ~58).

Size budgets hardened (tighten-only)
- agent-size / workflow-size / feat-3039 help-tiered: ceilings lowered to the
  current high-water mark and an assertTightCeiling anti-creep check added per
  tier. Fixed external-contract limits (description ≤100 chars, agent ≤100 KB)
  are intentionally left as-is — they are not grandfathered creeping budgets.

No user-facing behavior change (tests + tooling only); no USER_FACING_PREFIXES
touched, so no changeset fragment is required.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/install-minimal-hooks.test.cjs

@@ -140,7 +140,7 @@ describe('install-profiles: stageSkillsForMode', () => {
     try {
       assert.strictEqual(stageSkillsForMode(src, 'full'), src);
     } finally {
-      fs.rmSync(src, { recursive: true, force: true });
+      cleanup(src);
     }
   });
 
@@ -156,8 +156,8 @@ describe('install-profiles: stageSkillsForMode', () => {
           'phase.md', 'plan-phase.md', 'surface.md', 'update.md'],
       );
     } finally {
-      fs.rmSync(src, { recursive: true, force: true });
-      if (staged) fs.rmSync(staged, { recursive: true, force: true });
+      cleanup(src);
+      cleanup(staged);
     }
   });
 
@@ -170,8 +170,8 @@ describe('install-profiles: stageSkillsForMode', () => {
       const copied = fs.readFileSync(path.join(staged, 'plan-phase.md'), 'utf8');
       assert.strictEqual(copied, original);
     } finally {
-      fs.rmSync(src, { recursive: true, force: true });
-      if (staged) fs.rmSync(staged, { recursive: true, force: true });
+      cleanup(src);
+      cleanup(staged);
     }
   });
 
@@ -191,8 +191,8 @@ describe('install-profiles: stageSkillsForMode', () => {
       staged = stageSkillsForMode(src, 'minimal');
       assert.deepStrictEqual(fs.readdirSync(staged), ['plan-phase.md']);
     } finally {
-      fs.rmSync(src, { recursive: true, force: true });
-      if (staged) fs.rmSync(staged, { recursive: true, force: true });
+      cleanup(src);
+      cleanup(staged);
     }
   });
 });
@@ -211,7 +211,7 @@ describe('install-profiles: cleanupStagedSkills', () => {
       assert.ok(!fs.existsSync(a));
       assert.ok(!fs.existsSync(b));
     } finally {
-      fs.rmSync(src, { recursive: true, force: true });
+      cleanup(src);
     }
   });
 
@@ -230,7 +230,7 @@ describe('install-profiles: cleanupStagedSkills', () => {
       const after = process.listenerCount('exit');
       assert.ok(after - before <= 1, `expected <=1 new exit listener, got ${after - before}`);
     } finally {
-      fs.rmSync(src, { recursive: true, force: true });
+      cleanup(src);
       cleanupStagedSkills();
     }
   });
@@ -261,7 +261,7 @@ describe('install-profiles: cleanupStagedSkills', () => {
     } finally {
       fs.copyFileSync = realCopy;
       fs.mkdtempSync = realMkdtemp;
-      fs.rmSync(src, { recursive: true, force: true });
+      cleanup(src);
       cleanupStagedSkills();
     }
   });
@@ -296,7 +296,7 @@ describe('install: --minimal honoured for every runtime in --global mode', () =>
         );
         assert.strictEqual(manifestAgentCount(manifest), 0);
       } finally {
-        fs.rmSync(root, { recursive: true, force: true });
+        cleanup(root);
       }
     });
   }
@@ -315,7 +315,7 @@ describe('install: --minimal honoured for every runtime in --local mode', () =>
         );
         assert.strictEqual(manifestAgentCount(manifest), 0);
       } finally {
-        fs.rmSync(root, { recursive: true, force: true });
+        cleanup(root);
       }
     });
   }
@@ -333,7 +333,7 @@ describe('install: Cline --minimal (rules-based, no skills/ dir)', () => {
         assert.strictEqual(manifestAgentCount(manifest), 0);
         assert.ok(fs.existsSync(path.join(configDir, '.clinerules')));
       } finally {
-        fs.rmSync(root, { recursive: true, force: true });
+        cleanup(root);
       }
     });
   }
@@ -358,7 +358,7 @@ describe('install: on-disk skill files match manifest for --minimal', () => {
             assert.deepStrictEqual(gsdAgents, []);
           }
         } finally {
-          fs.rmSync(root, { recursive: true, force: true });
+          cleanup(root);
         }
       });
     }
@@ -385,7 +385,7 @@ describe('install: manifest records mode for both profiles', () => {
       const agentCount = Object.keys(m.files || {}).filter(k => k.startsWith('agents/')).length;
       return { mode: m.mode, skillCount, agentCount };
     } finally {
-      fs.rmSync(targetDir, { recursive: true, force: true });
+      cleanup(targetDir);
     }
   }
 
@@ -439,7 +439,7 @@ describe('install-minimal-backcompat: --minimal and --profile=core produce same
       const profileMarker = fs.existsSync(markerPath) ? fs.readFileSync(markerPath, 'utf8').trim() : null;
       return { mode: m.mode, skillCount, profileMarker };
     } finally {
-      fs.rmSync(targetDir, { recursive: true, force: true });
+      cleanup(targetDir);
     }
   }
 
@@ -518,7 +518,7 @@ describe('install: Codex full → minimal downgrade cleans stale agent state', (
       }
       assert.ok(fs.existsSync(configPath));
     } finally {
-      fs.rmSync(targetDir, { recursive: true, force: true });
+      cleanup(targetDir);
     }
   });
 });
@@ -545,7 +545,7 @@ describe('install: Claude full → minimal downgrade removes stale agents', () =
       assert.ok(remaining.includes('my-custom-agent.md'));
       assert.deepStrictEqual(remaining.filter(f => f.startsWith('gsd-')), []);
     } finally {
-      fs.rmSync(targetDir, { recursive: true, force: true });
+      cleanup(targetDir);
     }
   });
 });