Add stale PR indicators with configurable thresholds

[Mash4-4-4-4]

Summary

Added stale PR indicators in the PR Analytics section to help users quickly identify pull requests that have been open for too long.

Closes #257

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

Changes Made

• Added stale PR detection logic based on configurable thresholds
• Added threshold selector for 7 / 14 / 30 days
• Added stale PR count chip in the PR Analytics section
• Added stale PR list with orange "Stale" badges
• Added clickable links to open stale PRs directly
• Extended PR metrics API response to include PR metadata required for stale calculations

How to Test

Steps for the reviewer to verify this works:

1. Open the dashboard page
2. Navigate to the PR Analytics section
3. Verify stale PR count appears above the metrics cards
4. Change the threshold dropdown between 7 / 14 / 30 days
5. Confirm stale PR count updates correctly
6. Verify stale PRs display orange "Stale" badges
7. Click a stale PR entry and verify it opens the corresponding GitHub PR link

Screenshots (if UI change)

Add screenshots showing:

• stale PR count chip
• threshold selector
• stale PR list with badges

Checklist

• Linked issue in summary
• npm run lint passes locally
• No TypeScript errors (npm run type-check)
• Self-reviewed the diff
• Added/updated tests if applicable

[vercel]

@Mash4-4-4-4 is attempting to deploy a commit to the PRIYANSHU DOSHI's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Priyanshu-byte-coder]

Changes Required

1. Interface concatenation — missing newline

+interface PullRequest {
+  ...
+}interface PRMetricsBase {   // ← no newline between closing } and next interface

Add a blank line between the two interface declarations.

2. Indentation inconsistency throughout
Multiple code blocks are misaligned relative to the surrounding code:

• items: Array<{ block in the inline type (4-space instead of matching outer indent)
• const prs = data.items.map(...) block is indented as if inside the previous if but sits at function scope
• return { open, merged, ... } block is unindented vs the function body
• const [staleDays, setStaleDays] in PRMetrics.tsx placed at wrong indent level
• const isStale and const stalePRs appear at file scope instead of component scope

Run a formatter (Prettier) before submitting — the inconsistent indentation will cause lint failures.

3. Performance: 30 parallel GitHub API calls per dashboard load
getAverageFirstReviewHours does Promise.all(prs.slice(0, 30).map(fetchFirstReviewTimestamp)) — 30 concurrent API calls every time the PR Analytics card loads. For users with many PRs this is slow and risks hitting GitHub rate limits. The result should be wrapped in withMetricsCache (from PR #311) with a reasonable TTL.

4. Missing EOF newline in PRMetrics.tsx
File ends with } and no trailing newline.

5. Extra blank lines in fetchPRMetrics

async function fetchPRMetrics(token: string): Promise<PRMetricsBase> {
+
+  
  const searchRes = ...

Remove the two extra blank lines at the start of the function.

The stale PR feature (threshold selector + stale list) is a solid addition — address the above and this can merge.