Feature/daq questdb uns path

[CuAuPro]

📌 Description

This PR introduces Unified Namespace (UNS) path support for tags and persists it in QuestDB DAQ storage.

• What problem does this solve?
  • Tags had no explicit UNS metadata field, and QuestDB DAQ records did not store UNS path information.
  • This made it harder to align DAQ data with a unified naming model across datasources.
• What was changed?
  • Added top-level tag.unsPath metadata.
  • Added UNS visibility in device tag list (icon indicator + tooltip when configured).
  • Added UNS Path field in Tag Options with duplicate-path validation (per device).
  • Added i18n key device.tag-uns-path across language files.
  • Extended QuestDB DAQ schema/write path to store uns_path and added backward-safe column migration.
• Why is this needed?
  • Enables consistent UNS mapping for tags.
  • Preserves UNS context in historical DAQ data for querying/integration.

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🧪 Type of Change

Please mark the relevant option:

• Bug fix
• New feature
• Refactoring
• Documentation
• Other

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🚫 Build Artifacts Check

Please confirm:

• [x ] I did NOT commit /client/dist
• [x ] I did NOT commit generated Angular build output
• Only source files are included

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🔍 Checklist

• Code follows project coding standards
• I tested my changes locally
• Documentation updated if required
• Issue opened (for major changes)

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📚 Documentation Checklist (if applicable)

• The documentation builds locally with mkdocs serve
• All links were tested
• Images use relative paths (e.g. images/example.png)
• No references to the old GitHub Wiki
• Navigation updated in mkdocs.yml (if required)

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📝 Additional Notes

• UNS uniqueness validation is enforced in the UI against other tags in the same device.

[unocelli]

@CuAuPro Thank you very much for the QuestDB + UNS work, this is a great direction.

I reviewed #2220 as merge target (it includes #2213) and I have one merge-readiness request:

1. Please make QuestDB backend loading runtime-safe when packages are not installed (guarded import + safe handling/fallback), so users not using QuestDB remain fully compatible.

Minor UI note (optional): in QuestDB settings, please use an explicit QuestDB host label instead of the SMTP host label.

With this adjustment, this looks very good to merge.