refactor: implement three-layer agent architecture (agents / prompts / skills)

Layer 1 — src/agents/ (thin agent definitions, no prompt text)
  registry.ts   — AgentConfig, registerAgent(), getAgent(), AGENTS proxy, pick()
  orchestrator.ts, coder.ts, pm.ts, marketing.ts — one file each, just metadata + tool picks
  index.ts      — barrel: imports prompts then agents (correct registration order)

Layer 2 — src/prompts/ (prompt text separated from agent logic)
  loader.ts     — registerPrompt(), resolvePrompt() with {{variable}} substitution
  orchestrator.ts, coder.ts, pm.ts, marketing.ts — prompt templates as registered strings
  orchestrator.ts now uses resolvePrompt('orchestrator', { knowledge }) instead of
  inline SYSTEM_PROMPT const; {{knowledge}} variable injects project memory cleanly.
  agent-runner.ts uses resolvePrompt(config.promptId) per agent turn.

Layer 3 — src/tools/skills.ts (new skills capability)
  list_skills(repo)      — lists .skills/<name>/SKILL.md directories from a Gitea repo
  get_skill(repo, name)  — reads and returns the markdown body of a skill file
  Orchestrator and all agents now have get_skill in their tool sets.
  Orchestrator also has list_skills and references skills in its prompt.

Also fixed:
  - server.ts now passes history + knowledge_context from request body to orchestratorChat()
    (these were being sent by the frontend but silently dropped)
  - server.ts imports PROTECTED_GITEA_REPOS from tools/security.ts (no more duplicate)
  - Deleted src/agents.ts (replaced by src/agents/ directory)

Made-with: Cursor

dist/agents/registry.js

@@ -0,0 +1,34 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.AGENTS = void 0;
+exports.registerAgent = registerAgent;
+exports.getAgent = getAgent;
+exports.allAgents = allAgents;
+exports.pick = pick;
+const tools_1 = require("../tools");
+const _registry = new Map();
+function registerAgent(config) {
+    _registry.set(config.name, config);
+}
+function getAgent(name) {
+    return _registry.get(name);
+}
+function allAgents() {
+    return [..._registry.values()];
+}
+/**
+ * Backwards-compatible AGENTS object — populated as agents register.
+ * server.ts uses AGENTS[name] and Object.values(AGENTS).
+ */
+exports.AGENTS = new Proxy({}, {
+    get(_target, prop) { return _registry.get(prop); },
+    ownKeys() { return [..._registry.keys()]; },
+    getOwnPropertyDescriptor(_target, prop) {
+        const v = _registry.get(prop);
+        return v ? { configurable: true, enumerable: true, value: v } : undefined;
+    }
+});
+/** Pick tools from ALL_TOOLS by name. */
+function pick(names) {
+    return tools_1.ALL_TOOLS.filter(t => names.includes(t.name));
+}