test(W7c): match retro clock rule case-insensitively, drop proximity regex

W7c conversion (t02 #11, #12).

Removed assertion groups (invariant -> remaining protection):
- /NEVER from `date`/ (caps): today comes from the session reminder, not the
  system clock -> kept free: /session reminder/ and /never from `date`/i.
- /(?:disclosure[\s\S]{0,200}narrative|narrative[\s\S]{0,200}disclosure)/
  (200-char word-proximity window): offline/local-only runs disclose that the
  window is not freshness-verified -> kept free: the exact disclosure string
  'offline run, window not freshness-verified' (it reaches the retro output),
  RETRO_REF disclosure and the GUARD_* script checks; gate judge
  'retro/SKILL.md instructions'.

Mutation pass (scratch worktree, retro/SKILL.md.tmpl): 4/4 as expected;
allowing `date` or deleting the disclosure string goes red; lowering NEVER
and rewording the narrative clause stays green. Log:
.context/mutation-regression-1624-retro-stale-base.md.

test/regression-1624-retro-stale-base.test.ts

@@ -124,17 +124,15 @@ describe("#1624 retro guard — branch D: stale-base BLOCK", () => {
   test("today comes from the session reminder, never the system clock", () => {
     const body = readTmpl();
     expect(body).toMatch(/session reminder/);
-    expect(body).toMatch(/NEVER from `date`/);
+    expect(body).toMatch(/never from `date`/i);
   });
 });
 
 describe("#1624 retro guard — disclosure must reach the narrative", () => {
   test("skip paths carry a disclosure line into the retro output", () => {
     const body = readTmpl();
-    // The prose ties disclosure + narrative together so the retro output is
-    // never silently confidently-wrong on offline/local-only runs.
+    // The retro output is never silently confidently-wrong on offline/local-only runs.
     expect(body).toMatch(/offline run, window not freshness-verified/);
-    expect(body).toMatch(/(?:disclosure[\s\S]{0,200}narrative|narrative[\s\S]{0,200}disclosure)/);
   });
 
   test("non-default analyzed ref is disclosed (RETRO_REF)", () => {