Fix README Edge quickstart to use runner profiles explicitly

[DeliciousBuding]

Problem

The README quickstart suggests starting Edge with --agent-default claude-code, but that flag only changes the default adapter ID. It does not select the Claude Code runner profile or set the runner command. With no --runner-profile or --runner-command, the Edge process still uses the built-in mock executor fallback.

This can make a first-time user believe they are running the real Claude Code path while the local smoke path is actually exercising the mock executor.

Evidence

• README.md:113-116 recommends:
  • go run ./cmd/agenthub-edge --addr 127.0.0.1:3210 --agent-default claude-code
• edge-server/cmd/agenthub-edge/main.go:108-115 defines separate flags for --runner-profile, --runner-command, and --agent-default.
• edge-server/cmd/agenthub-edge/main.go:152-188 only applies runtime command defaults when --runner-profile is set to claude-code, codex, or opencode.
• edge-server/cmd/agenthub-edge/main.go:158-163 documents the mock profile/fallback behavior when no runner command or agent profile is configured.
• README.md:118-124 later lists --runner-profile examples, but the main recommended command above them still implies that --agent-default claude-code is enough for a real Claude Code run.

Impact

Onboarding and product validation can produce a false sense of real-runtime coverage. A contributor can run the README command, start Desktop, see the app work, and assume Claude Code was exercised even though the process path did not launch the Claude CLI.

Suggested fix

• Change the recommended Edge command to use an explicit runtime profile, for example --runner-profile claude-code when the user wants real Claude Code.
• Keep a separate mock/smoke command that intentionally uses --runner-profile agenthub-runner-mock.
• Explain the difference between:
  • --runner-profile: chooses the executor/runtime command preset;
  • --agent-default: chooses the default adapter ID when a run does not specify one.
• Keep the local-auth-token example aligned with the current smoke script if documented near the quickstart.

Acceptance

• README no longer implies that --agent-default claude-code launches Claude Code by itself.
• The quickstart has one explicit mock command and one explicit real-runtime command.
• The documented command matches edge-server/cmd/agenthub-edge/main.go flag behavior.
• No private paths, local operator details, tokens, or deployment evidence are added.