Completed personas UI reachability and fixed the missing backend ResolveSpec registrations that blocked it.

- Added Personas navigation/page wiring in the Svelte admin shell.
- Added a personas overview page with tabs for personas, parts, and traits.
- Expanded the persona inspector to load linked parts, traits, skills, guardrails, and arc state.
- Found that `/api/rs/public/agent_parts` and related persona routes were missing because `internal/app/resolvespec_admin.go` manually whitelists ResolveSpec models.
- Registered persona-related ResolveSpec models: `agent_personas`, `agent_parts`, `agent_traits`, persona join tables, arc tables, and `persona_arc`.
- Allowed ResolveSpec mutations for `agent_personas`, `agent_parts`, and `agent_traits`.
- Verified the `internal/app` package still compiles with `env GOCACHE=/tmp/amcs-go-cache go test -run '^$' ./internal/app`.

Follow-up:

- Automated ResolveSpec model registration generation with `relspec templ`.
- Added `scripts/templates/resolvespec_models.tmpl`.
- Updated `scripts/generate-models.sh` to generate `internal/app/resolvespec_models_generated.go`.
- Removed the handwritten `resolveSpecModels()` from `internal/app/resolvespec_admin.go`.
- Extended `scripts/patch-generated-models.sh` to fix current relspec output quirks:
  - incorrect `persona_arc` primary-key cast
  - unused `resolvespec_common` imports in join-table models
- Added focused tests covering persona entity presence and persona mutation allowlisting.