chore: hygiene sweep — dead code, role race, user lookup, stale files

One pass over the LOW-tier review items plus two folded issues:

- Delete validate_journal_entry (dead since the Fava migration; it
  validated the pre-string-amount model) with its exports, unused
  crud imports, and tests. Beancount validates entries now.
- Migration m006: UNIQUE index on user_roles(user_id, role_id) after
  deduping; assign_user_role inserts with ON CONFLICT DO NOTHING and
  returns the existing assignment — closes the auto-assign
  check-then-act race on concurrent logins.
- Extract _get_username_from_user_id (110 lines in views_api, fresh
  LNbits Database per call inside per-row hot paths) into
  user_lookup.py with one shared core-DB handle, a 60s TTL cache and
  a batch get_usernames API (review #18).
- Receivable-entry responses report CLEARED, matching the flag the
  formatter actually writes; PENDING misled the UI (libra-#35).
- Replace the remaining print() calls in tasks.py with logger.
- get_all_accounts derives valid roots from
  account_utils.ACCOUNT_TYPE_ROOTS instead of a hardcoded tuple, and
  the no-op per-test rate-limit reset is gone (libra-#54).
- Delete migrations_old.py.bak, MIGRATION_SQUASH_SUMMARY.md,
  docs/PHASE*_COMPLETE.md and the rendered .html; .gitignore data/
  (it holds the runtime .lnbits_auth_key secret).
- Track docs/CODE-REVIEW-2026-06.md with finding statuses updated for
  the PR #55-#59 + chore/hygiene series.
- CLAUDE.md notes LNbits pins Pydantic v1: keep .dict(), don't
  "modernize" to .model_dump().

Note: format_payment_entry's is_payable docstring (flagged in review
follow-up) turned out to be consistent with the body — no change.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/validation.py

@@ -18,81 +18,6 @@ class ValidationError(Exception):
         self.details = details or {}
 
 
-def validate_journal_entry(
-    entry: Dict[str, Any],
-    entry_lines: List[Dict[str, Any]]
-) -> None:
-    """
-    Validate a journal entry and its lines (Beancount-style with single amount field).
-
-    Checks:
-    1. Entry must have at least 2 lines (double-entry requirement)
-    2. Entry must be balanced (sum of amounts = 0)
-    3. All lines must have account_id
-    4. No line should have amount = 0 (would serve no purpose)
-
-    Args:
-        entry: Journal entry dict with keys:
-            - id: str
-            - description: str
-            - entry_date: datetime
-        entry_lines: List of entry line dicts with keys:
-            - account_id: str
-            - amount: int (positive = debit, negative = credit)
-
-    Raises:
-        ValidationError: If validation fails
-    """
-    # Check minimum number of lines
-    if len(entry_lines) < 2:
-        raise ValidationError(
-            "Journal entry must have at least 2 lines",
-            {
-                "entry_id": entry.get("id"),
-                "line_count": len(entry_lines),
-            }
-        )
-
-    # Validate each line
-    for i, line in enumerate(entry_lines):
-        # Check account_id exists
-        if not line.get("account_id"):
-            raise ValidationError(
-                f"Entry line {i + 1} missing account_id",
-                {
-                    "entry_id": entry.get("id"),
-                    "line_index": i,
-                }
-            )
-
-        # Get amount (Beancount-style: positive = debit, negative = credit)
-        amount = line.get("amount", 0)
-
-        # Check that amount is non-zero (zero amounts serve no purpose)
-        if amount == 0:
-            raise ValidationError(
-                f"Entry line {i + 1} has amount = 0 (serves no purpose)",
-                {
-                    "entry_id": entry.get("id"),
-                    "line_index": i,
-                }
-            )
-
-    # Check entry is balanced (sum of amounts must equal 0)
-    # Beancount-style: positive amounts cancel out negative amounts
-    total_amount = sum(line.get("amount", 0) for line in entry_lines)
-
-    if total_amount != 0:
-        raise ValidationError(
-            "Journal entry is not balanced (sum of amounts must equal 0)",
-            {
-                "entry_id": entry.get("id"),
-                "total_amount": total_amount,
-                "line_count": len(entry_lines),
-            }
-        )
-
-
 def validate_balance(
     account_id: str,
     expected_balance_sats: int,