Docs: rewrite getting-started guide for webhook-only, two-image, autonomous devloop

[zbloss]

What to build

Rewrite docs/getting-started.md to reflect the new architecture: two images (no poller, no Discord bot), webhook ingress as a hard prerequisite, fully autonomous Dev Loop with no approval gates, and all new Helm values documented.

Acceptance criteria

• Step 1 is webhook ingress setup: documents Cloudflare Tunnel (reference docs/cloudflare-tunnel.md), cloud load balancer, and ngrok as options; explains that https://<your-domain>/webhook/github must be reachable by GitHub
• Step 2 documents creating the GitHub webhook in the enrolled repo pointing at the tunnel URL, subscribing to issues, pull_request_review, and issue_comment events
• github-webhook-secret Kubernetes Secret creation documented
• devloop-bot setup documented: create a GitHub account, generate a fine-grained PAT with Contents/Pull requests/Issues (read/write) and Checks (read) permissions, create the PAT as a Kubernetes Secret
• getting-started.md documents all new Helm values: temporalWorker.maxConcurrentJobs, temporalWorker.ciFixMaxIterations, temporalWorker.executeMaxIterations, temporalWorker.maxQuestionsPerPhase, temporalWorker.agentGithubLogin, agent.gitName, agent.gitEmail, summarization.enabled, summarization.cronSchedule, summarization.webhookUrl
• Expected pods section shows only two devloop pods (devloop-agent-base not a running pod; devloop-temporal-worker is the only long-running deployment)
• "How issue triggering works" section describes the webhook model, not the polling model
• No references to poller, discordBot, Discord tokens, or approval gates remain
• Project Registry schema table updated: pr_reviewer docstring updated to "GitHub login requested as reviewer after CI Fix Loop and Review phases complete"
• Configuration reference table updated to remove poller/Discord settings and add all new settings

Blocked by

• Infra: remove devloop-poller image, Helm template, and CI pipeline #70, Refactor: remove nightly DevLoop Temporal schedule #71, Refactor: remove Discord Bot; replace all workflow notifications with GitHub Issue comments via devloop-bot #72, Infra: job dispatch queue — dedicate devloop-job-dispatch Temporal queue for Agent Execution Jobs with maxConcurrentJobs limit #73, Refactor: remove Plan Gate and Merge Gate; DevLoopWorkflow runs fully autonomously #74, Refactor: Execute phase retry loop — retry on zero-commit result up to execute_max_iterations #75, Refactor: replace Remediation phase with Phase.CI_FIX loop up to ci_fix_max_iterations #76, Feat: Phase.ANSWER — spawn a fresh agent to answer mid-run questions instead of waiting for a human #77, Feat: PRCommentWorkflow and webhook routing for pull_request_review and issue_comment events #78, Feat: Summarization delivery via GitHub Issue (default) and optional outbound webhook URL #79 — all implementation issues complete