refactor(template): match single-harness (hyperguild) architecture (infra#178)

The template carried the old multi-tool/agentsquad-era CAD-executor scaffold.
Refresh it to the consolidated single-harness reality (hyperguild#75/#76):
Claude Code + hyperguild, session-based, brain + gitea MCP. No dispatch
automation added (out of scope — dispatch stays manual until real friction
warrants it).

Removed (multi-tool + dead generator + deployed-agent-era):
- .aider.conf.yml, .aider.conventions.md, .cursorrules
- .context/ (mcp.json, PROJECT.md, system-prompt.txt)
- agent-policy.yaml (k8s NetworkPolicy scaffold)
- scripts/context-sync.sh (generated the above from .context/PROJECT.md — now
  input-less) + its context:sync* Taskfile tasks

Added / updated:
- .mcp.json (root, hyperguild-shaped: brain + gitea, Bearer env tokens)
- CLAUDE.md / AGENTS.md / README.md → single-harness workflow (issue →
  hyperguild session → PR → report-back comment → brain capture)
- AGENT_BOUNDARIES.md kept (harness-agnostic egress/scope guidance); repointed
  its two references to the removed agent-policy.yaml

Left alone: cd.yml, Dockerfile, Taskfile (build/test), go.mod, cmd/, internal/,
pkg/, .claude/. No dangling refs to removed files (verified). Refs infra#178.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -11,6 +11,16 @@ go mod tidy
 task run
 ```
 
+## Harness & workflow
+
+Single harness: **Claude Code + hyperguild** — session-based (start a session, it works, it
+stops). No push-triggered dispatch. MCP connections live in `.mcp.json`: **brain** (knowledge)
+and **gitea** (issues/PRs — the audit trail); provide `BRAIN_MCP_TOKEN` and `GITEA_MCP_TOKEN`.
+
+Work flows: **issue → hyperguild session → PR (`task check` gate) → report-back comment on the
+issue → brain capture if the learning is durable**. See `AGENTS.md` / `CLAUDE.md` for the full
+context, `AGENT_BOUNDARIES.md` for runtime scope.
+
 ## Observability
 
 Set `OTLP_ENDPOINT=http://jaeger.d-ma.be:4318` to emit traces. Each invocation produces: