feat(calendarium@kami911): add Calendarium desklet v1.0

[KAMI911]

A rich, highly customizable calendar and astronomical information desklet for the Cinnamon Desktop.

Features implemented:

• Date & time display with customizable strftime format, 12/24-hour clock, optional seconds
• Traditional month names: Old Hungarian, Old English (Anglo-Saxon), Old German
• Moon phase: locally calculated phase symbol, name, and age in days
• Sunrise & sunset: locally calculated from configurable GPS coordinates (default: Budapest)
• Western zodiac sign with Unicode symbol
• Chinese zodiac year animal and element
• New Year countdown: days remaining until next January 1st
• Name days: today plus up to 5 days lookahead (Hungarian, German, English datasets)
• Holidays: locale-aware public holiday datasets
• Folk days: traditional calendar entries per locale
• Wikipedia integration (opt-in, requires internet): on-this-day births & deaths, article of the day
• Solstice and equinox calculations
• Geocoder support for coordinate-based location lookup
• Gettext-based i18n with .po translation files and makepot support
• Configurable settings schema with rich UI options
• Stylesheet for visual customization

[KAMI911]

I reviewed the code with few tools:

══ 1/2 Semgrep SAST (JS + secrets + OWASP) ══
✔ No findings

┌─────────────┐
│ Scan Status │
└─────────────┘
  Scanning 44 files tracked by git with 582 Code rules:
                                                                                                                        
  Language      Rules   Files          Origin      Rules                                                                
 ─────────────────────────────        ───────────────────                                                               
  <multilang>      39      44          Community     582                                                                
  json              3      22                                                                                           
  js               68      12                                                                                           
                                                                                                                        
                
                
┌──────────────┐
│ Scan Summary │
└──────────────┘
✅ Scan completed successfully.
 • Findings: 0 (0 blocking)
 • Rules run: 110
 • Targets scanned: 44
 • Parsed lines: ~100.0%
 • No ignore information available
Ran 110 rules on 44 files: 0 findings.

══ 2/2 njsscan (Node.js / JavaScript security) ══
✔ No security issues

[KAMI911]

It is working, but I have no idea how an untrusted people like me, can prove that code is not harmful?
Current state with Hungarian language:

[KAMI911]

@claudiux & @fredcw

What should I do to get this into the repo? Thanks.