Add dedicated environment settings page and test-in-environment (#4798)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - Agents run inside environments (local, SSH, E2B sandbox)
> - Operators need to configure and manage these environments
> - But environment settings were buried inside the general company
settings page, making them hard to find
> - Additionally, when testing an agent from the configuration form, the
test always ran locally regardless of which environment was selected
> - This PR moves environments into a dedicated top-level company
settings section and wires the "Test Environment" button to run inside
the selected environment
> - The benefit is operators can find and manage environments more
easily, and the test button now validates the actual environment the
agent will use

## What Changed

- Added a dedicated `CompanyEnvironments` settings page with its own
route and sidebar entry
- Updated `CompanySettingsSidebar` and `CompanySettingsNav` to include
the new environments section
- Modified the agent test route (`POST /agents/:id/test`) to accept an
optional `environmentId` parameter
- Updated all adapter `test.ts` handlers to resolve and use the
specified execution target environment
- Added `resolveTestExecutionTarget` to `execution-target.ts` for remote
environment test resolution with cwd fallback
- Moved the "Test Environment" button and its feedback display into the
`NewAgent` page footer for better UX flow

## Verification

- `pnpm test` — all existing and new tests pass
- `pnpm typecheck` — clean
- Manual: navigate to Company Settings, confirm "Environments" appears
as a top-level section
- Manual: configure an agent with a non-local environment, click "Test
Environment", confirm the test runs inside that environment

## Risks

- Low risk. UI-only routing change for the settings page. The
test-in-environment change adds an optional parameter with a local
fallback, so existing behavior is preserved when no environment is
specified.

## Model Used

Codex GPT 5.4 high via Paperclip.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

ui/src/components/access/CompanySettingsNav.test.tsx

@@ -58,6 +58,8 @@ describe("CompanySettingsNav", () => {
   it("maps company settings routes to the expected shared tab value", () => {
     expect(getCompanySettingsTab("/company/settings")).toBe("general");
     expect(getCompanySettingsTab("/PAP/company/settings")).toBe("general");
+    expect(getCompanySettingsTab("/company/settings/environments")).toBe("environments");
+    expect(getCompanySettingsTab("/PAP/company/settings/environments")).toBe("environments");
     expect(getCompanySettingsTab("/company/settings/access")).toBe("access");
     expect(getCompanySettingsTab("/PAP/company/settings/access")).toBe("access");
     expect(getCompanySettingsTab("/company/settings/invites")).toBe("invites");
@@ -77,6 +79,7 @@ describe("CompanySettingsNav", () => {
         value: "access",
         items: [
           { value: "general", label: "General" },
+          { value: "environments", label: "Environments" },
           { value: "access", label: "Access" },
           { value: "invites", label: "Invites" },
         ],

ui/src/components/access/CompanySettingsNav.tsx

@@ -4,6 +4,7 @@ import { useLocation, useNavigate } from "@/lib/router";
 
 const items = [
   { value: "general", label: "General", href: "/company/settings" },
+  { value: "environments", label: "Environments", href: "/company/settings/environments" },
   { value: "access", label: "Access", href: "/company/settings/access" },
   { value: "invites", label: "Invites", href: "/company/settings/invites" },
 ] as const;
@@ -11,6 +12,10 @@ const items = [
 type CompanySettingsTab = (typeof items)[number]["value"];
 
 export function getCompanySettingsTab(pathname: string): CompanySettingsTab {
+  if (pathname.includes("/company/settings/environments")) {
+    return "environments";
+  }
+
   if (pathname.includes("/company/settings/access")) {
     return "access";
   }