chore(ci): address CI lint findings (#545)

This addresses all of zizmor's non-pedantic findings, and adds a
workflow to proactively flag any more that come in.

Key changes:

* I've hash-pinned all actions references. Dependabot will continue to
keep these updated and will update the hash comments as well.
* I've marked every `actions/checkout` with `persist-credentials: false`
except for one that actually needs persisted credentials (which I've
explicitly enabled with an explanatory comment)
* I've dropped some workflow-level permissions in favor of job-level
permissions that were already provisioned.
* I fixed two small template injections caused by expanding output
contexts. I think these were not exploitable in practice, but fixing
them is good for defense in depth (and makes spellcheck work nicely on
these steps).

---------

Signed-off-by: William Woodruff <william@astral.sh>

.github/workflows/codeql-analysis.yml

@@ -21,6 +21,8 @@ on:
     branches:
       - main
 
+permissions: {}
+
 jobs:
   analyze:
     name: Analyze
@@ -39,11 +41,13 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+        with:
+          persist-credentials: false
 
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@v3
+        uses: github/codeql-action/init@3c3833e0f8c1c83d449a7478aa59c036a9165498 # v3.29.11
         with:
           languages: ${{ matrix.language }}
           source-root: src
@@ -55,7 +59,7 @@ jobs:
       # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
       # If this step fails, then you should remove it and run the build manually (see below)
       - name: Autobuild
-        uses: github/codeql-action/autobuild@v3
+        uses: github/codeql-action/autobuild@3c3833e0f8c1c83d449a7478aa59c036a9165498 # v3.29.11
 
       # ℹ️ Command-line programs to run using the OS shell.
       # 📚 https://git.io/JvXDl
@@ -69,4 +73,4 @@ jobs:
       #   make release
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@v3
+        uses: github/codeql-action/analyze@3c3833e0f8c1c83d449a7478aa59c036a9165498 # v3.29.11