feat: ADR-0035 4h — ALTER TABLE … RENAME TO

The one genuinely new low-level op in Phase 4: a native engine RENAME TO
plus one-transaction reconciliation (commit-db-last) of everything the
engine does not track —

- every metadata row naming the table: __rdbms_playground_columns, both
  ends of __rdbms_playground_relationships (FK parent, child, and
  self-referential), and __rdbms_playground_table_checks;
- the CSV file, via the existing persistence rewrite+delete path
  (rewritten_tables=[new], deleted_tables=[old]) — no new method;
- CHECK text that qualifies a column with the old table name
  (T.age → U.age, column- and table-level): the engine rewrites the live
  CHECK but the stored text would drift and break a fresh rebuild (a
  planning-/runda finding); rewrite_check_table_qualifier keeps them in
  step. Bounded — a CHECK references only its own table.

Grammar: a fifth AlterTableAction (RenameTable { new }), added by
splitting the `rename` verb into one branch with an inner Choice on a
distinct second keyword (column vs to); the new-name slot mirrors the
CREATE TABLE name slot (NewName + reject_internal_table validator).

Refusals are engine-neutral and case-insensitive (the engine matches
names that way): same-name, case-only, existing-target, __rdbms_*, and
non-existent source. Auto-named indexes and relationships keep their
stale names (only table-name columns update — §6 scope). One undo step;
advanced-mode only; closes the rename half of C1.

Tests: 8 Tier-3 e2e + rewrite-helper unit tests + parse-dispatch tests.
Full suite 1903 passing / 0 failing / 1 ignored; clippy clean.

src/friendly/strings/en-US.yaml

@@ -274,6 +274,7 @@ help:
         alter table <T> add column <col> <type> [not null] [unique] [default …] [check …]
         alter table <T> drop column <col>
         alter table <T> rename column <old> to <new>
+        alter table <T> rename to <new>
         alter table <T> alter column <col> type <type>
         alter table <T> add [constraint <name>] check (<expr>) | unique (<col>, …) | foreign key (<col>) references <P>[(<col>)]
         alter table <T> drop constraint <name>   — evolve a table's columns and constraints (advanced SQL)
@@ -482,6 +483,7 @@ parse:
       alter table <Table> add column <Name> <Type> [not null] [unique] [default <expr>] [check (<expr>)]
       alter table <Table> drop column <Name>
       alter table <Table> rename column <Old> to <New>
+      alter table <Table> rename to <NewName>
       alter table <Table> alter column <Name> type <Type>
       alter table <Table> add [constraint <Name>] check (<expr>) | unique (<col>, ...) | foreign key (<col>) references <Parent>[(<col>)]
       alter table <Table> drop constraint <Name>

src/friendly/translate.rs

@@ -62,6 +62,7 @@ pub enum Operation {
     AddColumn,
     DropColumn,
     RenameColumn,
+    RenameTable,
     ChangeColumnType,
     AddRelationship,
     DropRelationship,
@@ -93,6 +94,7 @@ impl Operation {
             Self::AddColumn => "add column",
             Self::DropColumn => "drop column",
             Self::RenameColumn => "rename column",
+            Self::RenameTable => "rename table",
             Self::ChangeColumnType => "change column",
             Self::AddRelationship => "add relationship",
             Self::DropRelationship => "drop relationship",