Add governed solver islands for matrix multiplication

[ucsandman]

Matrix-multiplication research now keeps three bounded populations of development-verified solver programs. Mutation and crossover use the existing routing, allowance, deadline, and pause checks. Other plugins keep their current generation path.

Paired providers receive the same frozen parents and prompt bytes. Resume validates program and prompt hashes, restores the original development baseline, and records a lost response as indeterminate without issuing the call again. The dashboard shows population occupancy and clickable candidate ancestry.

Validation:

• Full check: 275 tests passed, 5 skipped; Ruff passed; 77 Python files compiled.
• Real Docker probe: 15 exact matrix evaluations, four locally stubbed generations, mutation and crossover exercised, all populations bounded at three parents. Completed resume performed zero additional work.
• Desktop and 390px mobile checks passed. Independent browser check reported zero console errors and failed requests.

The probe used unchanged solver variants and made zero live provider calls. It produced no confirmed improvement or publication claim.