feat(agents): "save as persona template" on agent card + sidebar

[tellaho]

What & why

Adds an opt-in "Save as persona template" action so a configured managed agent can be saved as a reusable persona template — wired consistently across the surfaces where a user manages an agent. Part of the #1201 line of UX work.

Based on kennylopez-agents-page-cards (#1199), not main — the action lives on exactly the surface #1199 rewrites (agent action menus → card ⋮). Basing here lands it on the UI that actually ships and avoids a double-merge into dead UI. Targets that branch as a draft so it merges into Kenny's work.

Surfaces

• Card ⋮ menu (AgentActionItems) — item gated !agent.personaId, so it only appears on agents that aren't already persona-backed.
• Sidebar agent profile (UserProfilePanel → ProfileQuickActions overflow ⋮) — gated canEditAgent (owner + managed agent). Tucked in an overflow ⋮ to keep the quick-action row lean.
• Persona actions menu — intentionally untouched. The thing is already a persona, so "save as persona" there would be nonsense — absence is correct.

How

• Mirrors the existing duplicatePersonaDialogState prefilled-dialog pattern: saveAsPersonaTemplateDialogState(agent) prefills the persona editor (name, system prompt, model, provider, env vars; reverse-maps agentCommand → runtime), leaves namePool empty for the user to fill, and opens the existing PersonaDialog so the user reviews before anything is created.
• No new backend / IPC — produces a CreatePersonaInput through the existing create mutation.
• New focused hook useSaveAsPersonaTemplate for surfaces outside the Agents page (the sidebar), with toast-based error handling.
• Naming-boundary comment in personaLibraryCopy.ts: UI says "persona template", backend stays persona (kind:30175); symbols deliberately not renamed.
• Provider carried across (lossless, on ManagedAgent) — a databricks agent saves as a databricks template. (Reversed an earlier "leave provider unset" call once we confirmed provider is on the row type.)

Guardrails held

• Did not touch buildUnifiedGroups or the card-grid structure — pure wiring.
• The UnifiedAgentsSection.tsx change tipped the 1000-line file-size gate; resolved by extracting the shared AgentActionItems into its own file (the sanctioned "split, don't override" path) — a pure lift, no logic change. File now 869 lines.

Part 1 (regression guard)

Verified CreateAgentDialog.handleSubmit never sets personaId (persona-less by construction) and added 6 regression tests, incl. an explicit "default create stays persona-less" guard.

Checks

pnpm typecheck ✅ · pnpm check ✅ (biome + file-sizes + px-text) · pnpm test ✅ 1138/1138 · pre-push hooks green.

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Draft for review. Targets kennylopez-agents-page-cards.

[tellaho]

Reviewer note — runtime reverse-map on first open.

The sidebar "Save as persona template" lazily loads ACP runtimes only when the dialog opens (useSaveAsPersonaTemplate flips the query's enabled flag in the same tick as open()). On the very first open, runtime discovery may not have resolved yet, so the command→runtime reverse-map can't find a match and the dialog falls back to its default-runtime behavior.

This is intentional and degrades gracefully — the user just picks the runtime themselves, same as a fresh persona create. A naive "re-seed once runtimes load" fix was prototyped and rejected: PersonaDialog seeds its local fields on [initialValues, open], so re-deriving initialValues after load would clobber any in-progress edits. The snapshot-on-open behavior is the correct tradeoff.