Add full Team 2890 roster — all 18 members with profiles

Students:
- fox.md (electrician)
- big-papa.md (student coach)
- jacob-firebreaker019.md (driver, 2026)
- jacob-m-jawarrior.md (programmer)
- ryan.md (operator)
- riley.md (technician) — updated with full profile
- steven.md (human player)
- alex-c.md (mentor, 21yr FRC vet)
- matthew.md (observer)
- kiera.md (team mascot)

Leadership/Mentors:
- gina-nakahara-clark.md (founding teacher)
- mr-douglas.md (programming mentor)
- walt.md (head mentor)
- chris-slater.md (lead coach)
- jackie.md (team mom)
- kp.md (rules guy)

Alumni:
- jacoby-powell.md (alumni/mentor)
- greyson-w.md (alumni/mentor, top coder)

Each profile includes: role, training track, status, emoji nickname, hub links

entities/walt.md

@@ -0,0 +1,45 @@
+---
+type: mentor-profile
+date: 2026-03-13
+updated: 2026-05-05
+discord: TBD
+role: head-mentor
+track: mechanical
+nickname: "Walt"
+emoji: "🛡️💥"
+status:
+  mentorship: active
+  expertise: intermediate
+---
+
+# Walt — Head Mentor
+
+## Who They Are
+- **Role:** Head Mentor
+- **Nickname:** Walt
+- **Emoji:** 🛡️💥
+- **Team:** 2026 season
+
+## Expertise Areas
+- Bumper construction — "making pretty looking, semi-functional bumpers that last until Riley hits things"
+- Mechanical assembly
+- Competition readiness
+
+## Training Progress
+
+| Track | Level | Status |
+|-------|-------|--------|
+| Mechanical | Intermediate | Active mentor |
+| Bumpers | Expert | Active mentor |
+
+## Notes
+- Old guy — brings experience from previous seasons
+- Known for bumper durability — bumpers survive until Riley crashes into things 💥
+- Positive mentorship style
+
+## Related Training Hubs
+- [[mechanical-hub]] — mechanical assembly, bumper rules
+
+---
+
+*Profile managed by MrC.*