[codex] orient promptc to Codex MCP

[andesdevroot]

What changed

This PR orients PROMPTC toward Codex as the primary MCP client surface and removes the active Claude Desktop coupling from the runtime, installer, and docs.

Why it changed

The local runtime already worked as an MCP stdio server, but the project still had host-specific logging and installation paths tied to Claude Desktop. The CLI path was also incomplete because rootCmd and typed SDK methods were missing, which caused contributor workflows to fail.

Main changes

• added cmd/promptc/root.go so the Cobra CLI has a working root command
• implemented typed Analyze and Optimize methods in pkg/sdk/sdk.go
• fixed cmd/promptc/fix.go to use the typed SDK methods safely
• updated cmd/promptc/main.go so MCP actor/client reporting is configurable and defaults to codex-desktop
• aligned runtime version reporting to v0.3.1 in boot logs, dashboard, and health metadata
• rewrote install.sh to register PROMPTC through codex mcp add instead of Claude Desktop config injection
• updated README.md so quick start and positioning reflect Codex-first local MCP usage

Impact

PROMPTC is now easier to install and operate in Codex, and the open source checkout is coherent again for local contributor workflows.

Validation

• go test ./...
• go build -o promptc ./cmd/promptc/main.go
• manual runtime boot check showing PROMPTC v0.3.1 iniciado — cliente=codex-desktop