feat: add Enum & Value Completeness to /review critical checklist

New CRITICAL review category that traces new enum values, status strings,
and type constants through every consumer outside the diff. Catches the
class of bugs where a new value is added but not handled in all switch/case
chains, allowlists, or frontend-backend contracts.

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

review/checklist.md

@@ -48,6 +48,13 @@ Be terse. For each issue: one line describing the problem, one line with the fix
 - LLM-generated values (emails, URLs, names) written to DB or passed to mailers without format validation. Add lightweight guards (`EMAIL_REGEXP`, `URI.parse`, `.strip`) before persisting.
 - Structured tool output (arrays, hashes) accepted without type/shape checks before database writes.
 
+#### Enum & Value Completeness
+When the diff introduces a new enum value, status string, tier name, or type constant:
+- **Trace it through every consumer.** Read (don't just grep — READ) each file that switches on, filters by, or displays that value. If any consumer doesn't handle the new value, flag it. Common miss: adding a value to the frontend dropdown but the backend model/compute method doesn't persist it.
+- **Check allowlists/filter arrays.** Search for arrays or `%w[]` lists containing sibling values (e.g., if adding "revise" to tiers, find every `%w[quick lfg mega]` and verify "revise" is included where needed).
+- **Check `case`/`if-elsif` chains.** If existing code branches on the enum, does the new value fall through to a wrong default?
+To do this: use Grep to find all references to the sibling values (e.g., grep for "lfg" or "mega" to find all tier consumers). Read each match. This step requires reading code OUTSIDE the diff.
+
 ### Pass 2 — INFORMATIONAL
 
 #### Conditional Side Effects
@@ -101,8 +108,8 @@ Be terse. For each issue: one line describing the problem, one line with the fix
 CRITICAL (blocks /ship):          INFORMATIONAL (in PR body):
 ├─ SQL & Data Safety              ├─ Conditional Side Effects
 ├─ Race Conditions & Concurrency  ├─ Magic Numbers & String Coupling
-└─ LLM Output Trust Boundary      ├─ Dead Code & Consistency
-                                   ├─ LLM Prompt Issues
+├─ LLM Output Trust Boundary      ├─ Dead Code & Consistency
+└─ Enum & Value Completeness      ├─ LLM Prompt Issues
                                    ├─ Test Gaps
                                    ├─ Crypto & Entropy
                                    ├─ Time Window Safety