Restructure Troubleshooting into a hub with per-area pages (#814)

* Restructure Troubleshooting into a hub with per-area pages

- Add a Troubleshooting hub (/help/troubleshooting) with icon/chip cards and a "Still stuck?" CTA
- Split NetBird Client troubleshooting into an overview + per-OS pages (Linux, Windows, macOS, Android, iOS)
- Split Self-hosted troubleshooting into an overview + per-area pages (installation, IdP, dashboard, certificates, connectivity, database)
- Split "Report bugs and issues" into Community Support and NetBird Support pages
- Add Troubleshooting resource connectivity and a NetBird Cloud pending-approval page
- Add DNS troubleshooting Issue 8 (Windows NRPT rule blocked by a lingering GPO)
- Cross-reference the new pages from networks, DNS, and reverse-proxy docs; update nav

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* Address review: client terminology, dead props, labels, cross-links

- Use "client" instead of "agent" across the client troubleshooting pages (headings, prose, anchors)
- Remove unused source: props from the Troubleshooting hub tiles
- Relabel the "NetBird Cloud" grouping to "Cloud & identity" (SSO/provisioning also apply to self-hosted)
- Add a Tiles title on the report-bug landing; add reverse-proxy -> resource-connectivity cross-link
- Fix comma splices introduced by the em-dash cleanup in relayed-connections

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* Add client-side hash redirect for moved self-hosted anchors

Old deep links like /selfhosted/troubleshooting#debugging-turn-connections now
forward to the per-area page, since next.config redirects can't act on the URL fragment.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* Apply docs-skill review: conventions + reshape area pages

- "open source" (no hyphen), expand NRPT on first use, descriptive alt text + captions on TURN images
- Fix inherited "Netbird" casing in the client glossary
- Reshape the six self-hosted area pages to Symptom -> likely causes (ordered) -> Fix -> Confirm, preserving anchored headings

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* Fix two typos in client glossary (CodeRabbit)

- "nunning" -> "running" in the glossary
- possessive "it's" -> "its" in the routing-table sentence

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* docs: fix two broken links in troubleshooting pages

- database: point the "upgrade path" link at /selfhosted/maintenance/upgrade;
  selfhosted-quickstart has no #upgrade anchor so the old link landed at page top
- client: add HashRedirect so old #net-bird-agent-status deep links forward to
  the renamed #net-bird-client-status section on the same page

* docs: address review follow-ups (deep-link redirects + client casing)

- self-hosted troubleshooting: extend the HashRedirect map with the per-issue
  (###-level) anchors from the old single page, so old deep links land on the
  exact sub-section of the new area page rather than just the page top
- client glossary: lowercase "NetBird client" in the peer-a/peer-b entries
  (house convention) and fix "linux" -> "Linux"

* docs: review polish — fix image class + first-use acronym glosses

- connectivity: fix bad CSS class imagewrapper-nig -> imagewrapper on the
  TURN-test screenshot (the typo'd class matched no style and broke zoom)
- gloss acronyms on first use: GPO (DNS Issue 8), IdP/SSO (identity-provider),
  ACME (certificates), CORS (dashboard)

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: Jack Carter <128555021+SunsetDrifter@users.noreply.github.com>

src/pages/selfhosted/troubleshooting/database.mdx

@@ -0,0 +1,30 @@
+export const description =
+  "Self-hosted NetBird database troubleshooting: the Management service failing to start after an upgrade, and recovery after power loss."
+
+# Database issues
+
+Database and migration problems on a self-hosted deployment. For other areas, start from [Troubleshooting](/selfhosted/troubleshooting).
+
+## Management service won't start after upgrade
+
+**Symptom**: After an upgrade, the Management container fails to start or crash-loops.
+
+**Likely causes and fixes** (most common first):
+
+1. **A failed schema migration.** Check `docker compose logs management` for migration errors. This is the usual cause and the logs name the failing step.
+2. **A skipped intermediate version.** Major version jumps may require stepping through intermediate releases. Follow the [upgrade path](/selfhosted/maintenance/upgrade) for your version.
+3. **A corrupt or partially-migrated database.** If the migration can't be completed, restore from a pre-upgrade backup and retry the upgrade.
+
+**Confirm**: `docker compose ps` shows `management` as `Up`, and its logs end with the service listening rather than a migration error.
+
+## Data corruption after power loss
+
+**Symptom**: Services don't start cleanly after an unexpected shutdown.
+
+**Likely causes and fixes** (most common first):
+
+1. **A stale lock file.** Check for and remove a leftover database lock if the process that held it is gone.
+2. **An interrupted write.** Review all service logs to find which store is failing. For SQLite, run an integrity check on the database file.
+3. **An unrecoverable file.** If the store can't be repaired, restore from the most recent backup.
+
+**Confirm**: All services report `Up` in `docker compose ps`, and peers reconnect with `netbird status` showing `Management: Connected`.