[Bug/UX]: Dropdown filters allow selecting Department/Semester combos with no existing data, causing confusing "Found 0" results

[riyanshigupta890-cloud]

Describe the issue
On both /syllabus and /notes, selecting certain Department + Semester combinations
returns "Found 0 [syllabi/resources]" — even though a related resource exists for
the same university under "All" filters.

Steps to reproduce (Notes page)

1. Go to /notes
2. Set University: NIT Trichy, Department: All, Semester: All
3. Observe "Found 1 resources" → "Operating Systems - Detailed Notes" tagged #Semester 4
4. Now set Department: Computer Science, Semester: Semester 3
5. Observe "Found 0 resources"

Steps to reproduce (Syllabus page)

1. Go to /syllabus
2. University: IIT Delhi, Department: All, Semester: All → "Found 1 syllabi"
   (Electronics Engineering - Semester 4)
3. Set Department: Computer Science, Semester: Semester 1 → "Found 0 syllabi"

Possible causes
Not sure if this is a filter-matching bug or simply a lack of seed data in the
database for these combinations — flagging both possibilities:

1. If data exists but filters aren't matching it correctly → logic bug
2. If no data exists for these combos → the dropdowns shouldn't let users pick
   combinations with zero backing data, or the empty state should clarify this
   isn't a glitch (e.g. "No resources yet for this filter — try browsing all")

Why this matters
Either way, the current experience is confusing for users since they can't tell
if something is broken or just unavailable.

Screenshots

[sayan-netizen]

i would like to contribute under GSSOC'26