refactor(lsm): finish SSTable and table shard naming

Applies the SSTable / table shard / freeze vocabulary from the previous
commit to code that came in from main, and to spots that commit missed:

- `get_lsm_stats` test fixtures in Rust and Python still sent the old
  `buckets` / `generations` keys, so the Rust test target no longer
  compiled and the Python tests would fail against `table_shards`.
- The Java javadoc example called a nonexistent `LsmWriteSpec.tableShard`,
  an over-rename of `LsmWriteSpec.bucket`; the README used the old
  `buckets()` / `generations()` accessors.
- Prose that still said bucket (for a shard), seal, L0, or flushed
  generations, and identifier-style "table_shard" / "tableShard" in prose.

`LsmWriteSpec::bucket`, `num_buckets`, the hash-bucket values in the
merge-insert router, and the `"Sealed"` status wire value are unchanged:
those name the sharding transform or a server value, not the shard.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

nodejs/__test__/table.test.ts

@@ -4908,7 +4908,7 @@ describe("LSM convergence and stats", () => {
     const conn = await connect(tmpDir.name);
     const table = await lsmTable(conn);
 
-    // checkpointLsm seals first, so it surfaces flushLsm's rejection.
+    // checkpointLsm freezes first, so it surfaces flushLsm's rejection.
     await expect(table.checkpointLsm()).rejects.toThrow(/not supported/i);
   });
 });

nodejs/lancedb/query.ts

@@ -467,7 +467,7 @@ export class StandardQueryBase<
    * {@link Table#setLsmWriteSpec}), reads are routed through the LSM scanner so
    * they also return data written via the `mergeInsert` LSM path that has not yet
    * been compacted into the base table (the active/frozen in-memory memtables and
-   * the flushed generations), deduplicated by primary key; a table without a spec
+   * the SSTables), deduplicated by primary key; a table without a spec
    * reads the base table.
    *
    * @param enable - `true` forces the LSM scanner and errors if the table has no

nodejs/lancedb/table.ts

@@ -815,7 +815,7 @@ export abstract class Table {
   /**
    * Freeze every table shard's active memtable into a new SSTable.
    *
-   * Returns once the seal is committed. Sealing an empty memtable is a no-op,
+   * Returns once the freeze is committed. Freezing an empty memtable is a no-op,
    * so this is safe to call repeatedly.
    * @returns {Promise<void>}
    */
@@ -852,9 +852,9 @@ export abstract class Table {
    */
   abstract checkpointLsm(): Promise<void>;
   /**
-   * Read live per-bucket LSM state.
+   * Read live per-table-shard LSM state.
    *
-   * Answers "how far behind is my fresh tier", "which bucket is hot", and
+   * Answers "how far behind is my fresh tier", "which table shard is hot", and
    * "why is my fresh-tier vector search brute-force". Mutates no table state.
    *
    * Resolves to `undefined` only when the LSM write path is not enabled.

nodejs/src/table.rs

@@ -1106,7 +1106,7 @@ impl From<lancedb::table::MemtableStats> for MemtableStats {
 #[napi(object)]
 #[derive(Clone, Debug)]
 pub struct TableShardStats {
-    /// The shard this table shard writes.
+    /// The id of this table shard.
     pub shard_id: String,
     /// `"Active"` or `"Sealed"` (drop-table 2PC in flight).
     pub status: String,