Fix dev server port conflicts across worktrees

[Eliezir]

Closes #290.

Summary

Fixes dev server port conflicts when running multiple worktrees in parallel (Conductor or plain git worktree). Before: only the first worktree's API binds :3001; other studios silently proxy to the stale first instance, so endpoints that only exist on the current branch return 404 in what looks like a UI bug. After: each worktree picks its own free API port, and its studio proxy follows.

As a bonus for parallel-worktree workflows, the browser tab title now reflects the workspace (Conductor workspace name, or current git branch as a fallback), so tabs are trivially distinguishable at a glance.

Previous	Conductor workspace	Branch fallback
ADT Studio	ADT Studio — Cool workspace	ADT Studio — Dev port conflicts

How

• scripts/dev.mjs — root dev orchestrator. Finds a free port (sequential scan from 3001), then spawns the existing pnpm --parallel dev with PORT and API_PROXY_TARGET threaded in as env vars. Also detects a workspace label (from CONDUCTOR_WORKSPACE_NAME, falling back to the current git branch's leaf segment) and forwards it as VITE_WORKSPACE_NAME.
• scripts/find-free-port.mjs — pure-Node port probe. Logic adapted from Zig's findFreePort in the zig/electron branch (apps/electron/src/main/api/port.ts).
• apps/studio/vite.config.ts — proxy target now reads API_PROXY_TARGET with http://localhost:3001 fallback.
• apps/studio/src/main.tsx — when VITE_WORKSPACE_NAME is set at dev time, appends it to document.title. Unset in production builds, so end users see the default title.
• apps/studio/src/vite-env.d.ts — type declaration for the new env var.
• package.json — root dev script now calls node scripts/dev.mjs. dev:api / dev:studio unchanged.

Approach

We went with a monorepo-level orchestrator because it's self-contained, tool-agnostic (works with plain git worktree, Conductor, multiple terminals), needs zero per-worktree config, and adds no dependencies. A more robust alternative would be a dedicated tool like Portless, which handles automatic subdomain routing with zero env wiring — at the cost of another dev dependency and per-developer setup.

Scope

Web dev only. The electron launch path already picks its own port via its own supervisor logic and is untouched. Production builds are also untouched: the api's PORT fallback stays 3001, vite build ignores server.proxy, and VITE_WORKSPACE_NAME is unset so the tab title is unchanged.

Test plan

• Run pnpm dev in one worktree → [dev] API port: 3001, studio on 5173
• Run pnpm dev in a second worktree concurrently → [dev] API port: 3002, studio on 5174, /api/* requests from the second studio hit the second worktree's API
• Temporary console.log on an api route in worktree 2, triggered from worktree 2's studio, appears in worktree 2's terminal (not worktree 1's)
• Under Conductor: each tab title reads ADT Studio — <workspace name>
• Outside Conductor (plain worktree): tab title reads ADT Studio — <branch leaf> (e.g. Dev port conflicts for Eliezir/dev-port-conflicts)
• Solo pnpm dev:studio still proxies to :3001 and shows the plain ADT Studio title (backwards compatible)
• pnpm typecheck passes

[Eliezir]

Continuation of #295, which was auto-closed by GitHub when the head branch was renamed from Eliezir/dev-port-conflicts to eliezir/dev-port-conflicts to match the project's existing branch-naming convention. Same commits, same description.