docs: update out-of-date info in README.md, docs/, and manual/ (#1459)

This updates the `README.md`, `docs/`, and `manual/` to

* re-add `c2rust refactor` now that it's been resurrected.
* remove known limitations that have now been fixed (inline assembly,
C11 atomics, packed structs).
* remove references to things that have been removed (cross-checks,
Docker, Azure CI, `rustfmt-preview`, Lua scripting).
* recommend `godbolt.org` instead of `c2rust.com`, as it's actually
up-to-date and much nicer to use.
* recommend `bear` over `intercept-build`, as it's much more up-to-date
and not Linux-only anymore.
* update installation instructions to use `--locked`, which we get a lot
of issues about.
* update all the even older nightly references to `nightly-2022-08-08`,
except for the generated `nightly-2023-04-15`, which is on purpose and
up-to-date.
* update everything else to use `uv`, too (`test_translator.py` and
`c2rust-testsuite/test.py` already were, our main test scripts).

It doesn't, however,

* update `c2rust.com/manual`, as I'm not sure how to do that. But the
`README.md` does now warn that `c2rust.com/manual` is currently very
out-of-date and to refer to the in-tree sources instead.
* touch any of `manual/c2rust-refactor/doc/{ldoc.css,
scripting_api.html}`.
* update most dependencies. Many aren't needed or used anymore, or use
the wrong versions, but determining that needs more CI testing (our main
source of truth).

Author: kkysen

.github/workflows/ci.yml

@@ -98,7 +98,6 @@ jobs:
           # It's important that we keep `RUSTFLAGS` consistent between different steps
           # so that we don't have to rebuild everything.
           echo "RUSTFLAGS=-Clink-arg=-L/opt/homebrew/lib -Clink-arg=-Wl,-rpath,/opt/homebrew/lib" >> $GITHUB_ENV
-          
 
       - name: cargo build --release
         run: |
@@ -120,4 +119,4 @@ jobs:
           # causing tons of errors, so don't set that.
           # `test_translator.py` does not rebuild,
           # so changing `RUSTFLAGS` will not trigger a full rebuild.
-          uv run ./scripts/test_translator.py tests/
+          ./scripts/test_translator.py tests/

.github/workflows/internal-testsuite.yml

@@ -67,11 +67,11 @@ jobs:
           ${{ github.workspace }}/testsuite/tests/**/compile_commands.json
         key: ${{ runner.os }}-${{ hashFiles('**/Cargo.lock', '**/c2rust-ast-exporter/**/CMakeLists.txt', '**/examples/**/CMakeLists.txt') }}
 
-    - name: Cache Python - pip
-      uses: actions/cache@v4
-      with:
-        path: ~/.cache/pip
-        key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
+    - uses: astral-sh/setup-uv@v6
+
+    - name: Install Python Packages
+      run: |
+        uv tool install scan-build # for `intercept-build`
 
     # TODO(pl): Figure out why json-c fails when caching compile commands
     # - name: Get Image Version
@@ -88,7 +88,7 @@ jobs:
     #     key: ${{ runner.os }}-ccdb-${{ steps.get-image-ver.outputs.version }}
 
     - name: Provision Rust
-      run:  rustup component add rustfmt-preview rustc-dev
+      run:  rustup component add rustfmt rustc-dev
 
     - name: Provision Debian Packages
       run: |
@@ -111,17 +111,11 @@ jobs:
             librtmp-dev             \
             libtool                 \
             libzstd-dev             \
-            python3-setuptools      \
-            python3-wheel           \
             rcs                     \
             tcl-dev                 \
             tk-dev                  \
             zlib1g-dev
 
-    # installs intercept-build to $HOME/.local/bin
-    - name: Provision Python Packages
-      run: python3 -m pip install -r $GITHUB_WORKSPACE/testsuite/requirements.txt
-
     # Runs a single command using the runners shell
     # Working dir is /home/runner/work/c2rust/c2rust
     - name: Build c2rust
@@ -136,7 +130,7 @@ jobs:
         export PATH=$PWD/target/release:$HOME/.local/bin:$PATH
         echo "PATH=$PATH"
         export C2RUST_DIR=$PWD
-        python3 testsuite/test.py curl json-c lua nginx zstd libxml2 python2
+        ./testsuite/test.py curl json-c lua nginx zstd libxml2 python2
 
     - uses: actions/upload-artifact@v4
       with: