fix: re-lock the self-referencing git dep after the history rewrite

`crates/sylpheed-export` depends on THIS repository by tag:

    sylpheed-formats = { git = "…/Sylpheed.git", tag = "formats-pin-2026-09-01" }

and `Cargo.lock` pinned it to commit `#1cd5b8b1`. The issue-#49 history rewrite
replaced every commit, so `1cd5b8b1` no longer exists on the remote and the tag
now dereferences to `e2630413`.

⚠️ The failure is invisible here: `~/.cargo/git` still has the old object, so
builds on the machine that did the rewrite keep working. A clean checkout --
CI, or the other desktop -- cannot resolve the locked rev at all. That is the
worst shape for a breakage, which is why this was measured from an empty
CARGO_HOME rather than trusted to a local build.

`CONSOLIDATION.md` called this dependency out as the hard blocker for the
rewrite. It was not re-checked before the push; this is the fix.

The dependency's SOURCE is unchanged -- `crates/sylpheed-formats` has tree
`55461e46` at both the old and the new commit, so the rewrite never touched it
and the build result is identical.

Verified:
  * remote tag peels to e2630413, matching the new lock
  * `cargo fetch --locked` from an EMPTY CARGO_HOME -> exit 0
  * `cargo check -p sylpheed-export --locked` -> exit 0

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -221,7 +221,7 @@ version = "1.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "40c48f72fd53cd289104fc64099abca73db4166ad86ea0b4341abe65af83dadc"
 dependencies = [
- "windows-sys 0.61.2",
+ "windows-sys 0.60.2",
 ]
 
 [[package]]
@@ -232,7 +232,7 @@ checksum = "291e6a250ff86cd4a820112fb8898808a366d8f9f58ce16d1f538353ad55747d"
 dependencies = [
  "anstyle",
  "once_cell_polyfill",
- "windows-sys 0.61.2",
+ "windows-sys 0.60.2",
 ]
 
 [[package]]
@@ -2507,7 +2507,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
 dependencies = [
  "libc",
- "windows-sys 0.61.2",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -3824,7 +3824,7 @@ version = "0.50.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
 dependencies = [
- "windows-sys 0.61.2",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -4818,7 +4818,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys 0.12.1",
- "windows-sys 0.61.2",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -5116,7 +5116,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3a766e1110788c36f4fa1c2b71b387a7815aa65f88ce0229841826633d93723e"
 dependencies = [
  "libc",
- "windows-sys 0.61.2",
+ "windows-sys 0.60.2",
 ]
 
 [[package]]
@@ -5237,7 +5237,7 @@ dependencies = [
 [[package]]
 name = "sylpheed-formats"
 version = "0.1.0"
-source = "git+https://git.mc02.dev/fabi/Sylpheed.git?tag=formats-pin-2026-09-01#1cd5b8b1cb1f02eefc0865e1a1fe280e44831c9d"
+source = "git+https://git.mc02.dev/fabi/Sylpheed.git?tag=formats-pin-2026-09-01#e26304133732792cb1df5563c21df59471f5bf7d"
 dependencies = [
  "anyhow",
  "binrw",
@@ -5417,7 +5417,7 @@ dependencies = [
  "getrandom 0.3.4",
  "once_cell",
  "rustix 1.1.4",
- "windows-sys 0.61.2",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -5776,7 +5776,7 @@ checksum = "f2f6fb2847f6742cd76af783a2a2c49e9375d0a111c7bef6f71cd9e738c72d6e"
 dependencies = [
  "memoffset",
  "tempfile",
- "windows-sys 0.61.2",
+ "windows-sys 0.60.2",
 ]
 
 [[package]]
@@ -6294,7 +6294,7 @@ version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
 dependencies = [
- "windows-sys 0.61.2",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]