chore: prepare VS Code extension for Marketplace publishing

[amrmelsayed]

Summary

Gets the VS Code extension publishable on the Marketplace by adding the missing metadata and resolving identifier conflicts. The extension is now live at cluesmith.codev-vscode (3.0.0 stable).

Two commits

1. `chore: prepare VS Code extension for Marketplace publishing` (`d1ef54b6`)

Marketplace metadata (gaps that would have made the listing look unfinished):

• `icon`: `icons/codev.png` — copied from `marketing/logo.png` (1024×1024 PNG; the Marketplace doesn't accept SVG for the listing icon)
• `categories`: `["AI", "Other"]` for discoverability
• `keywords`: nine search terms (`ai`, `agent`, `claude`, `codev`, `agent-farm`, `multi-agent`, `autonomous`, `tower`, `spir`)
• `homepage`, `bugs.url` (issues), `qna` (Discussions, instead of Marketplace-hosted Q&A), `galleryBanner` (#1e1e1e dark), `pricing` ("Free")

Identifier rename (Marketplace global-uniqueness conflicts):

• `name`: `codev` → `codev-vscode` — the `codev` slug is taken by sk-aicoding.codev. Marketplace requires the `name` field to be globally unique, not just unique per publisher.
• `displayName`: `Codev` → `Codev for VS Code` — same conflict at the display level. Adopted the standard `X for VS Code` pattern.

Version alignment:

• `0.2.0` → `3.0.0` to align with the codev npm package's 3.0.x series. Stripped the codev RC suffix because the Marketplace doesn't accept SemVer pre-release tags (`-rc.12`); the `--pre-release` flag at publish time covers that channel separately.

Build / publish scripts:

• `vsix`: `vsce package --no-dependencies` (esbuild bundles deps inline; vsce's npm-ls walk fails in pnpm workspaces without this flag)
• `vscode:publish`: stable channel
• `vscode:publish:pre`: `--pre-release` channel (added explicitly because pnpm's `-- --pre-release` forwarding doesn't work cleanly through vsce)

2. `docs: update arch.md Marketplace identifier` (`cf667c0c`)

Updates the directory map's `cluesmith.codev` reference to `cluesmith.codev-vscode` so it matches the actual published identifier.

Publishing flow after this lands

```bash

Stable

pnpm --filter codev-vscode vscode:publish

Pre-release (use this for RCs)

pnpm --filter codev-vscode vscode:publish:pre
```

Both run `vscode:prepublish` (`pnpm package` → check-types + lint + esbuild --production) before uploading, so you don't need to `vsce package` first.

Live verification

The extension is already published as a result of getting through the conflicts during this PR's prep work:

• Listing: https://marketplace.visualstudio.com/items?itemName=cluesmith.codev-vscode
• Install: `code --install-extension cluesmith.codev-vscode`
• Confirmed via Marketplace gallery API: `flags: validated, public`, version 3.0.0 (stable)

Test plan

• `pnpm --filter codev-vscode vsix` builds a clean .vsix (52KB, includes `extension/icons/codev.png`, no `node_modules/`, no `src/`)
• `code --install-extension codev-vscode-3.0.0.vsix` succeeds
• `vsce publish --no-dependencies` succeeds against publisher `cluesmith`
• Listing renders the new icon, displayName "Codev for VS Code", description, README, GitHub links
• Sidebar smoke test: install from Marketplace (not local .vsix) and confirm sidebar/terminals work end-to-end

Out of scope

• VS Code extension version is now intentionally a different lane from the codev npm version (`3.0.0` vs `3.0.0-rc.12`). The lockstep plan (Lockstep version bumps to prevent stale codev-core on release #692) needs a follow-up to handle the SemVer pre-release stripping for the extension specifically.