feat: add rename_column support for ALTER TABLE

[william-ch-databricks]

🥞 Stacked PR

Use this link to review incremental changes.

• stack/alter-table-1-refactor-state [Files changed] [MERGED]
  • stack/alter-table-2-supports-data-files [Files changed] [MERGED]
    • stack/alter-table-3-framework-add-column [Files changed] [MERGED]
      • stack/alter-table-4-set-nullable [Files changed]
        • stack/alter-table-5-column-mapping-add [Files changed]
          • stack/alter-table-6-drop-column [Files changed]
            • stack/alter-table-7-rename-column [Files changed]
              • stack/alter-table-8-operation-string [Files changed]
                • stack/alter-table-9-is-blind-append [Files changed]

---

What changes are proposed in this pull request?

Adds RenameColumn as a terminal operation in the ALTER TABLE framework:

• Renaming type state ensures rename cannot be combined with other operations
• Buildable trait + sealed module for shared build() between Modifying and Renaming
• Case-insensitive sibling conflict check via sibling_names_at_path
• Physical identity (column ID + physical name) preserved via with_name
• Runtime defense-in-depth: RenameColumn must be the sole operation

Full integration test suite covering add/drop/rename/set_nullable, chaining,
sequential alters, checkpoints, time travel, and append-only tables.

How was this change tested?

[william-ch-databricks]

Range-diff: stack/alter-table-6-drop-column (a82d990 -> 7a91a31)

kernel/src/snapshot.rs

@@ -8,17 +8,6 @@
  use crate::transaction::Transaction;
  use crate::utils::require;
  use crate::LogCompactionWriter;
- 
-     /// Compute the lazy CRC for a post-commit snapshot by applying a [`CrcDelta`].
-     ///
--    /// For CREATE TABLE, builds a fresh CRC from the `crc_delta`. For existing tables, applies
--    /// the `crc_delta` to the current CRC if loaded, otherwise carries forward the existing lazy CRC.
-+    /// For existing tables (including ALTER TABLE), applies the `crc_delta` to the current CRC
-+    /// if loaded, otherwise carries forward the existing lazy CRC. CREATE TABLE handles CRC
-+    /// construction separately in `Transaction::into_committed`.
-     fn compute_post_commit_crc(&self, new_version: Version, crc_delta: CrcDelta) -> Arc<LazyCrc> {
-         let crc = self
-             .lazy_crc
      /// before building an [`AlterTableTransaction`] that can be committed.
      ///
      /// [`AlterTableTransaction`]: crate::transaction::alter_table::AlterTableTransaction

kernel/src/transaction/alter_table.rs

@@ -8,4 +8,12 @@
 +// use within the crate and for tests.
  #![allow(unreachable_pub)]
  
- use std::marker::PhantomData;
\ No newline at end of file
+ use std::marker::PhantomData;
+ 
+         Ok(Transaction {
+             span,
+-            read_snapshot: Some(read_snapshot),
++            read_snapshot_opt: Some(read_snapshot),
+             effective_table_config,
+             should_emit_protocol: false,
+             should_emit_metadata: true,
\ No newline at end of file

_{Reproduce locally: git range-diff 7173e80..a82d990 4236b5c..7a91a31 | Disable: git config gitstack.push-range-diff false}

[codecov]

Codecov Report

❌ Patch coverage is 96.98661% with 27 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.54%. Comparing base (6486bd2) to head (4691658).

Files with missing lines	Patch %	Lines
kernel/src/transaction/schema_evolution.rs	96.96%	15 Missing and 6 partials ⚠️
kernel/src/actions/mod.rs	96.36%	0 Missing and 2 partials ⚠️
kernel/src/schema/mod.rs	90.47%	1 Missing and 1 partial ⚠️
kernel/src/transaction/builder/alter_table.rs	94.73%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2391      +/-   ##
==========================================
+ Coverage   88.40%   88.54%   +0.13%     
==========================================
  Files         178      178              
  Lines       58235    59110     +875     
  Branches    58235    59110     +875     
==========================================
+ Hits        51485    52337     +852     
- Misses       4783     4798      +15     
- Partials     1967     1975       +8     

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