Document the codebase thoroughly and tighten type safety

Docs: per-folder README.md for packages/ (family overview + one per
package: service, events, API, extension points, TODOs), examples/,
and examples/echo-agent/; folder-level AGENTS.md (+ CLAUDE.md
symlinks) for packages/ and vendor/; module-level doc comments in
every packages/*/src file; richer JSDoc on all exported API
(event side effects, disposal contracts, error behavior). Root
AGENTS.md gains a "Type Safety and Documentation" policy section:
the codebase aims to be very type-safe and well documented; type
gymnastics are acceptable in core packages when they improve
plugin-author DX; verbose docs are fine as long as they stay strictly
in sync with the code.

Type safety: removed the upstream-inherited "noImplicitAny": false
from tsconfig.base.json — packages/* now compile under full strict
mode; vendor/loader and vendor/include set it locally (vendor/cordis
already did). Eliminated every `: any` / `as any` from packages and
examples (catch clauses use unknown + a CodedError narrowing type;
event data access uses discriminated-union narrowing).

Typed tool schemas: new @deepseek-ai/dsh-tools schema DSL —
SchemaSpec with per-property `required: true` booleans, type-level
InferArgs<S>, a runtime SchemaSpec → JSON Schema converter, and
defineTool() so first-party tools get typed execute(args) with zero
casts (raw JSON Schema still accepted for MCP interop; chosen over
schemastery because it targets JSON Schema generation directly).
echo-tool and all test tools migrated; +7 tests.

packages/agent/src/index.ts

@@ -1,3 +1,10 @@
+/**
+ * Agent registry service. Tracks live agents so plugins can find them without
+ * depending on the concrete loop package. Agent creation belongs to the loop.
+ *
+ * @module @deepseek-ai/dsh-agent
+ */
+
 import { Context, Service } from 'cordis'
 import type { Agent } from './types.ts'
 
@@ -22,7 +29,11 @@ export class AgentRegistry extends Service {
     super(ctx, 'agents')
   }
 
-  /** Register a live agent. Disposed with the calling fiber. */
+  /**
+   * Register a live agent. Throws if an agent with the same id is already
+   * registered. Emits `agent/created` on registration and `agent/disposed`
+   * when the calling fiber is disposed. Returns the disposer.
+   */
   register(agent: Agent): () => void {
     return this.ctx.effect(() => {
       if (this.store.has(agent.id)) {

packages/agent/src/types.ts

@@ -1,3 +1,14 @@
+/**
+ * Agent interface and event taxonomy. Every plugin programs against the
+ * `Agent` handle defined here; the concrete implementation lives in
+ * `@deepseek-ai/dsh-agent-loop`.
+ *
+ * Merge-extensible: `AgentOptions` supports declaration merging for
+ * plugin-specific creation options.
+ *
+ * @module @deepseek-ai/dsh-agent/types
+ */
+
 import type { ContentBlock, GenerateOptions, Message, MessageSource, StreamChunk } from '@deepseek-ai/dsh-llm'
 import type { Session, TurnEndReason } from '@deepseek-ai/dsh-session'