Name rust-analyzer everywhere the toolchain is installed

VS Code's rust-analyzer extension ships a server newer than 1.92.0
supports and prompts, on every window, to add one. Listing the component
in rust-toolchain.toml makes rustup supply the server matching the pin —
the same thing the pin buys everywhere else.

The cost lands outside the editor, which is why this is four files
rather than one. rustup reconciles that component list against the
installed toolchain on the first cargo call in the work tree and
downloads what is missing, inside whatever job happens to be running. An
unasked-for fetch in the middle of a build step is nobody's line item
and hard to find in a log. So every environment that builds this repo
names it too: baked into the Android image, and in the install step of
each CI job that rolls its own toolchain.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitea/workflows/traceability-check.yml

@@ -44,12 +44,17 @@ jobs:
           key: traces-${{ runner.os }}-${{ hashFiles('**/Cargo.lock') }}
 
       # Source-comment and markdown parsing only, so the minimal profile is
-      # enough — no system libraries and no components beyond cargo itself.
+      # enough — no system libraries and nothing this job itself needs beyond
+      # cargo. rust-analyzer is here anyway because rust-toolchain.toml lists
+      # it: rustup installs that file's components on the first cargo call in
+      # the work tree regardless, and a download named in the install step
+      # beats the same download appearing unannounced inside the gate.
       - name: Install Rust 1.92.0
         run: |
           set -e
           curl -fsSL https://sh.rustup.rs | sh -s -- \
-            -y --no-modify-path --profile minimal --default-toolchain 1.92.0
+            -y --no-modify-path --profile minimal --default-toolchain 1.92.0 \
+            --component rust-analyzer
           echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
 
       # The gate's own arithmetic is the thing being trusted, so its tests run