[edjubert]

Follow-up to #934 and #935.

Consecutive comments before ELSE, THEN, END, and GRANT/REVOKE keywords could be emitted in reverse order because only the last comment received the keyword anchor:

-- Before
select case when a then 1 /* second */ else /* first */ 2 end from t;
-- After
select case when a then 1 /* first */ /* second */ else 2 end from t;

Comments before END could also move into a nested CASE, or out into FROM when the last branch was a function call:

-- Before
select case when a then 1 else case when b then 2 else 3 /* outer */ end end from t;
-- After
select case when a then 1 else case when b then 2 else 3 end /* outer */ end from t;

The formatter now anchors every comment in a consecutive group to the same keyword and keeps mixed block/line comments on the same side of their node. Comments before a CASE's END are attached to that CASE and emitted after its complete final branch. CASE/END matching uses actual CASE nodes, parenthesis depth, and field-name context so names such as t.end and subquery aliases do not change the closing boundary.

Six new regression tests cover both layouts, mixed comment groups, GRANT/REVOKE, nested CASEs in THEN and ELSE, compound final expressions, keyword names, and idempotence.

Validation:

• cargo test -p pgls_pretty_print — 759 tests passed.
• cargo test -p pgls_pretty_print --test option_matrix -- --ignored — fixtures and PostgreSQL regression corpus across all 32 layout combinations.
• cargo clippy --all-targets --all-features.
• cargo fmt --all -- --check and git diff --check.