Add a MariaDB recovery page

[ideaship]

Gives bringing back a MariaDB/Galera cluster that stopped completely, for example after a power outage, its own page in the operations guide. The Recovery subsection in infrastructure.md becomes a pointer to it.

What the page covers

• Before you start — the MariaDB hosts and their count from osism get hosts -l mariadb, and database_password from osism vault view.
• Recover the cluster — osism apply mariadb-recovery, which starts the cluster from the member with the highest Galera sequence number and joins the others to it.
• Verify — wsrep status queried on every node directly, compared against the inventory count rather than what a running node reports, followed by OpenStack reads and a network create and delete from the manager.

The page stands on its own. Recovery is a routine operation, not part of restoring a backup, so it is kept apart from the MariaDB backup and restore guide:

• Add a MariaDB backup and restore guide #1093

The two PRs touch separate parts of infrastructure.md and merge cleanly in either order.

🤖 Generated with Claude Code

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Max errors	Warnings	Elapsed time
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✅ JSON	jsonlint	4		0		0	0.1s
✅ JSON	prettier	4		0		0	0.36s
✅ JSON	v8r	4		0		0	9.2s
✅ MARKDOWN	markdownlint	172		0		0	3.48s
✅ MARKDOWN	markdown-table-formatter	172		0		0	0.46s
✅ REPOSITORY	betterleaks	yes		no		no	0.91s
✅ REPOSITORY	checkov	yes		no		no	18.76s
✅ REPOSITORY	git_diff	yes		no		no	0.11s
✅ REPOSITORY	secretlint	yes		no		no	1.59s
✅ REPOSITORY	trufflehog	yes		no		no	4.24s
✅ SPELL	codespell	182		0		0	0.79s
✅ SPELL	lychee	182		0		0	16.88s
✅ YAML	prettier	6		0		0	0.62s
✅ YAML	v8r	6		0		0	7.7s
✅ YAML	yamllint	6		0		0	0.59s

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