refactor(ci): skip bincraft reinstall when image already has it (#72)

## Summary

bincraft is baked into the build-env images, but every workflow still unconditionally calls `pak::pak("git::.../bincraft.git")` (~30–60s per job).

Pin bincraft to a specific tag (currently `v4.0.2`) and guard the install on a version check.

```
- /opt/R/$R_VERSION/bin/R -q -e 'if (!requireNamespace("bincraft", quietly = TRUE) || packageVersion("bincraft") != "4.0.2") pak::pak("git::https://codefloe.com/rpkgs/bincraft.git@v4.0.2")'
```

- Image matches the pin → skip install entirely.
- Image is missing bincraft or has a different version → install the pinned tag (covers both broken bakes and intentional version bumps).
- Renovate customManager keeps the pin and the version-check string in sync whenever bincraft cuts a new tag (uses `git-tags` datasource against the bincraft repo).

Touches 43 `.crow` YAMLs + `renovate.json`.

Reviewed-on: #72

renovate.json

@@ -5,5 +5,19 @@
   ],
   "ignorePaths": [
     "docker/**"
+  ],
+  "customManagers": [
+    {
+      "customType": "regex",
+      "fileMatch": ["^\\.crow/.*\\.yaml$"],
+      "matchStrings": [
+        "packageVersion\\(\"bincraft\"\\) != \"(?<currentValue>[0-9.]+)\"",
+        "bincraft\\.git@v(?<currentValue>[0-9.]+)"
+      ],
+      "depNameTemplate": "bincraft",
+      "packageNameTemplate": "https://codefloe.com/rpkgs/bincraft.git",
+      "datasourceTemplate": "git-tags",
+      "extractVersionTemplate": "^v?(?<version>.+)$"
+    }
   ]
 }