Add sync error logging, extend error flash, fix unload saves

- Log workforce sync errors to backend stdout so they appear in docker logs
- Extend error flash from 5s to 15s so errors are readable
- Replace sendBeacon (POST-only) with keepalive fetch (PUT) on unload —
  sendBeacon was hitting 404s on all three unload saves

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/@babel/preset-env/data/built-in-modules.js

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+// TODO: Remove in Babel 8
+
+module.exports = require("@babel/compat-data/native-modules");

frontend/node_modules/@babel/preset-env/data/built-in-modules.json.js

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+// TODO: Remove in Babel 8
+
+module.exports = require("@babel/compat-data/native-modules");

frontend/node_modules/@babel/preset-env/data/built-ins.js

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+// TODO: Remove in Babel 8
+// https://github.com/vuejs/vue-cli/issues/3671
+
+module.exports = require("./corejs2-built-ins.json");

frontend/node_modules/@babel/preset-env/data/built-ins.json.js

@@ -0,0 +1,4 @@
+// TODO: Remove in Babel 8
+// https://github.com/vuejs/vue-cli/issues/3671
+
+module.exports = require("./corejs2-built-ins.json");

frontend/node_modules/@babel/preset-env/data/core-js-compat.js

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+// TODO: Remove in Babel 8
+
+module.exports = require("core-js-compat/data.json");

frontend/node_modules/@babel/preset-env/data/corejs2-built-ins.js

@@ -0,0 +1,3 @@
+// TODO: Remove in Babel 8
+
+module.exports = require("@babel/compat-data/corejs2-built-ins");

frontend/node_modules/@babel/preset-env/data/corejs2-built-ins.json.js

@@ -0,0 +1,3 @@
+// TODO: Remove in Babel 8
+
+module.exports = require("@babel/compat-data/corejs2-built-ins");

frontend/node_modules/@babel/preset-env/data/package.json

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+{ "type": "commonjs" }

frontend/node_modules/@babel/preset-env/data/plugins.js

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+// TODO: Remove in Babel 8
+
+module.exports = require("@babel/compat-data/plugins");

frontend/node_modules/@babel/preset-env/data/plugins.json.js

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+// TODO: Remove in Babel 8
+
+module.exports = require("@babel/compat-data/plugins");

frontend/node_modules/@babel/preset-env/data/shipped-proposals.js

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+// TODO: Remove in Babel 8
+
+const { pluginSyntaxMap, proposalPlugins, proposalSyntaxPlugins } = require("../lib/shipped-proposals");
+module.exports = { pluginSyntaxMap, proposalPlugins, proposalSyntaxPlugins };

frontend/node_modules/@babel/preset-env/data/unreleased-labels.js

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+// TODO: Remove in Babel 8
+
+module.exports = require("@babel/helper-compilation-targets").unreleasedLabels;