feat!: Email support using lettre

.cargo/config.toml

@@ -1,2 +1,8 @@
 [resolver]
 incompatible-rust-versions = "fallback"
+
+# TODO: Safe to remove once https://github.com/rust-lang/rust/issues/141626 gets resolved.
+# Also, see https://github.com/cot-rs/cot/pull/419/changes#r2636869773 for more info.
+[target.x86_64-pc-windows-msvc]
+linker = "rust-lld"
+rustflags = ["-C", "symbol-mangling-version=v0"]

.github/workflows/rust.yml

@@ -15,6 +15,10 @@ env:
   SCCACHE_GHA_ENABLED: true
   RUSTC_WRAPPER: sccache
 
+  _RUST_STABLE: &rust_stable stable
+  # Pinning the nightly version to a "stable" version to avoid CI breakages.
+  _RUST_NIGHTLY: &rust_nightly nightly-2025-11-11
+
 # See: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency.
 # This will ensure that only one commit will be running tests at a time on each PR.
 concurrency:
@@ -58,9 +62,9 @@ jobs:
         os: [ubuntu-latest, macos-latest, windows-latest]
         include:
           - rust: stable
-            version: stable
+            version: *rust_stable
           - rust: nightly
-            version: nightly
+            version: *rust_nightly
           - rust: MSRV
             version: "1.88" # MSRV
 
@@ -149,7 +153,7 @@ jobs:
         uses: dtolnay/rust-toolchain@master
         with:
           # cot_macros ui tests require nightly
-          toolchain: nightly
+          toolchain: *rust_nightly
 
       - name: Cache Cargo registry
         uses: Swatinem/rust-cache@v2
@@ -195,7 +199,7 @@ jobs:
         uses: dtolnay/rust-toolchain@master
         with:
           # branch coverage is currently optional and requires nightly
-          toolchain: nightly
+          toolchain: *rust_nightly
           components: llvm-tools-preview
 
       - name: Reclaim disk space
@@ -248,7 +252,7 @@ jobs:
         uses: dtolnay/rust-toolchain@master
         with:
           # nightly-only rustfmt settings
-          toolchain: nightly
+          toolchain: *rust_nightly
           components: rustfmt
 
       - name: Cache Cargo registry
@@ -299,7 +303,7 @@ jobs:
         uses: dtolnay/rust-toolchain@master
         with:
           # the `-Z` flag is only accepted on the nightly channel of Cargo
-          toolchain: nightly
+          toolchain: *rust_nightly
 
       - name: Cache Cargo registry
         uses: Swatinem/rust-cache@v2
@@ -368,7 +372,7 @@ jobs:
         uses: dtolnay/rust-toolchain@master
         with:
           # miri requires nightly
-          toolchain: nightly
+          toolchain: *rust_nightly
           components: miri
 
       - name: Cache Cargo registry