chore(cargo-anvil): regenerate .anvil.lock for anvil 0.9.0 after rebase

PR 169 has been green on all 28 checks and carries two approving automated
reviews, but GitHub reported `mergeable_state: dirty` and it could not merge.
The 2026-09-08 diary entry recorded exactly that state -- "both automated
reviews recommend approval, but the branch is currently dirty against `main`"
-- and left it as the outstanding blocker.

The conflict was entirely in `.anvil.lock`. `main` released cargo-anvil 0.9.0
(3bf8d54) with a new `catalog_checksum`, while this branch still carried the
0.8.0 header plus its own checksum for `justfiles/anvil/impact.just`, which the
branch regenerates because it edits
`crates/cargo-anvil/templates/justfiles/anvil/impact.just`. Both sides touched
the same two lines.

`.anvil.lock` is generated, so it was NOT hand-merged. At each conflicting step
the lock was taken from the rebase target and the final `chore: regenerate
.anvil.lock after rebase` commit -- whose entire content was the stale lock --
was dropped, then the file was rewritten by the tool itself with
`cargo run -p cargo-anvil -- anvil`. Hand-resolving the hunk was rejected: the
`catalog_checksum` is derived from the whole template catalog, so a plausible
manual merge can be textually reasonable and still wrong.

Verified rather than assumed:
- `cargo run -p cargo-anvil -- anvil --dry-run` before the regen reported
  "Manifest update required: .anvil.lock" -- i.e. the exact `regenerate-check`
  gate in `.github/workflows/regenerate-check.yml` would have failed.
- The regen produced only the two expected lines: the 0.9.0 catalog checksum
  and the `justfiles/anvil/impact.just` checksum. No generated file content
  changed, confirming the rebase preserved the reviewed behaviour.
- `--dry-run` afterwards reports 92 unchanged and no manifest update.
- `cargo +1.97 test -p cargo-anvil --all-features --locked`: 415 unit tests and
  all integration suites pass, including the 21 impact tests this branch
  rewrites.
- `just anvil-clippy` clean.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Vaiz

.anvil.lock

@@ -1,7 +1,7 @@
 version = 1
 tool = "anvil"
 tool_version = "0.9.0"
-catalog_checksum = "sha256:baa2a5e479fe8f466e8f54e71ef0c498e07ac225b59a61a76ee99d46d5498650"
+catalog_checksum = "sha256:2314355f946f7935bc0673b00faa5ae5a0ee6cd5c5abbbac44779cb45458abcf"
 
 [[file]]
 path = ".anvil/container/Dockerfile.dockerignore"
@@ -233,7 +233,7 @@ checksum = "sha256:dc42a4b2ed4a25e3a37b322dad209df34d7adca88bf3c4de60b2f8c1b396e
 
 [[file]]
 path = "justfiles/anvil/impact.just"
-checksum = "sha256:0b3a5c96dd33384b4c86ac02b17396bc1a9fe9c82edbc516a2ceea7f4fe3833d"
+checksum = "sha256:e565c20b662318d877a7e9b9c88187c99fc848a8294bf9c2bba31dd9fdb605f3"
 
 [[file]]
 path = "justfiles/anvil/mod.just"