[garvitshrma]

The documented debug flow doesn't work if the app has already been built; briefcase build --debug pdb and briefcase build --debug debugpy only reinstall requirements when -r is passed. The part that it only reinstalls if -r is used wasn't documented.

Changes:

1. Added -r to briefcase build examples on the PDB and VS Code how-to pages with a short explanation on why an -r is needed.
2. Added the equivalent -r note to the --debug section of run.md.
3. Minor fix not included in the issue: Changed the wording from VS Code debugger to PDB Debugger on the PDB page which might have been mistakenly copied from vscode.md.

Fixes #2621

PR Checklist:

• I will abide by the BeeWare Code of Conduct
• I have read and have followed the CONTRIBUTING.md file
• This PR was generated or assisted using an AI tool

Assisted-by: Claude Opus 5

[freakboy3742]

I've downgraded the release note to a misc - this is an important correction in the docs, but not something that needs to be called out in the next release notes. Otherwise, this is great - thanks for the PR!