Add thin_shrink and era_repair to Makefile and create manpages

[regulad]

The following changes have been introduced in this PR:

• New manpages for thin_shrink and era_repair
• Reorganize TOOLS array in Makefile, updating it to match src/bin/pdata_tools.rs exactly with thin_shrink and era_repair.
• Use TOOLS and MANPAGES to create symlinks and manpages repsectively.
• Update other thin_* manpages with a "SEE ALSO" section to mention thin_shrink.

This pull request has been created as a draft, as I do not have enough knowledge of the semantics of era_repair to populate the SYNOPSIS, DESCRIPTION, and EXAMPLES sections in the manpage.

I am slightly more familiar with thin_shrink since I have used it in my deployments; however, my knowledge is not comprehensive enough to write a manpage.

Help is requested from the maintainers @jthornber and @mingnus for the manpages era_repair and thin_shrink repsectively.

Thank you for the creation of this project, it has served exceptionally useful in my deployments.

[regulad]

With the help of an LLM (Moonshot Kimi 2.5) and some good old-fashioned legwork, I've fashioned a "provisional" set of manpages. Obviously, they need to be manually reviewed by a maintainer more familiar with the quirks than I.

[regulad]

There are still some issues with the instructions.

[mingnus]

I'll read through it later. I think you could separate the era_repair and thin_shrink man pages into different commits. Also, there was already a pending pull request suggesting similar Makefile changes, so I would cherry-picking the commit first.

I noticed the TOOLS list was reordered. Is there a functional reason for this change, or is it just for readability?