Fix lint error and align daily-logs tests with refactored route

[Copilot]

CI was failing due to one ESLint violation and 7 test failures introduced when the daily-logs API was refactored to use an internal auto-managed account instead of a user-supplied accountId.

Lint fix — components/layout/dashboard-shell.tsx

react-hooks/set-state-in-effect flagged a synchronous setTheme() call inside useEffect. Replaced with a lazy useState initializer:

// Before — triggers the lint rule
const [theme, setTheme] = useState<string>("light");
useEffect(() => {
  const stored = localStorage.getItem("theme");
  if (stored === "dark" || stored === "light") setTheme(stored);
}, []);

// After — reads localStorage once at init, no setState-in-effect
const [theme, setTheme] = useState<string>(() => {
  if (typeof window !== "undefined") {
    const stored = localStorage.getItem("theme");
    if (stored === "dark" || stored === "light") return stored;
  }
  return "light";
});

Test fixes — __tests__/api/daily-logs.test.ts

The route now always resolves the account via getOrCreateDailyLogsAccount() (account.findFirst → account.create). Tests were written against the old user-supplied accountId model.

• 5 GET tests: added mockAccountFindFirst setup (required before the Promise.all data fetch); removed mockAccountFindMany calls; dropped the stale json.accounts expectation (the route no longer returns an accounts array)
• POST "returns 400 when accountId is missing": accountId is optional in the schema and ignored by the route — updated to assert the request succeeds without it
• POST "returns 400 when account does not belong to user": validation no longer exists — replaced with a test for the getOrCreate creation path (adds mockAccountCreate to the mock graph and asserts account.create is called with the correct Daily Logs payload)

README

Updated coverage badge and stats (100% stmts / 98.9% branches / 100% fns, 234 tests across 19 files), corrected coverage threshold (≥95%), and corrected Next.js version (16).

Original prompt

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This section details on the original issue you should resolve

<issue_title>fix linting and add tests to achieve 100% coverage</issue_title>
<issue_description>I have made some changes, review all the code, analyze the project, then write tests to get maximum (~100%) coverage. Test for accuracy, correctness, functionality, usability and regression. Every calculation should be tested and validated. Also, make sure the entire project is linted and error and/or warning free. Then finally, update the readme.md file to update any inaccurate/conflicting/missing/outdated info and make sure the readme markets the entire app and its functionalities. </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes fix linting and add tests to achieve 100% coverage #16

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