Add Zopu dev bootstrap: git runtimes, Codex agent-os, dev agent

A vertical slice to bootstrap the product loop on the canonical zopu-code repo.

Primitives (packages/primitives, all tested + lint/type clean):
- GitRemoteRuntime: Gitea REST client (createIssue, createBranch,
  createPullRequest, listIssues, getIssue) as an Effect context service with
  a fetch-backed transport. Live-verified against puter/zopu-code.
- GitLocalRuntime: clone, addWorktree, commit, push, currentBranch,
  setRemoteUrl over a pluggable Shell (host subprocess now, AgentOS VM exec
  later). Tested against real temp git repos.
- agent-os: Codex support via @agentos-software/codex-cli — codexSoftware
  bundle (codex+git), makeCodexAgentOsConfig(), codexSessionEnv() for the
  OpenAI base URL/key.

Env:
- GITEA_URL/GITEA_TOKEN wired into convex.ts and convex.config.ts.
- .env.example documents the self-hosted git section.

Agents (packages/agents):
- zopu-dev: development agent that creates issues on the canonical repo and
  starts autonomous work runs. git-remote tools (create/list/branch/PR) wired
  to GitRemoteRuntime; start_workflow tool enqueues a work run.
- flue run zopu-dev verified live (lists/creates issues on real Gitea).

Backend (packages/backend):
- workflows.startIssueWork mutation: fetches a Gitea issue server-side and
  admits a queued work run. The Codex VM spawn body is the next step.

.env.example

@@ -32,3 +32,7 @@ AGENT_MODEL_BASE_URL=https://ai.example.com/v1
 AGENT_MODEL_API_KEY=replace-with-provider-api-key
 AGENT_MODEL_CONTEXT_WINDOW=262000
 AGENT_MODEL_MAX_TOKENS=131072
+
+# Self-hosted git (Gitea) — canonical repository host and API token
+GITEA_URL=https://git.openputer.com
+GITEA_TOKEN=replace-with-a-gitea-personal-access-token