Correct diff direction by swapping branch/commit parameters

[Wolfe1]

Swap branch and commit parameters when constructing Bitbucket diff specs so the diff shows what the source adds to the destination (additions as +, deletions as -). Apply the same reversal logic to branch and commit diffs and update the changelog to reflect the bug fix. This fixes incorrect PR diff classification and improves displayed diff accuracy.

Fixes #84

Before:

After:

[igorvelho]

I was investigating the very same issue, I just wonder if instead of hardcode the diff direction, you should introduce a parameter on the mcp tool to specify direction, like
{ "repoSlug": "myrepo", "sourceBranch": "feat-123", "destinationBranch": "master", "includeFullDiff": true, **"diffDirection": "sourceToDestination"** }

[Wolfe1]

@igorvelho I honestly don't understand why someone would want this though?

And if they really did want a diff in the other direction then they could just switch the source and destination rather than there being some flag that changes the intended purpose.