feat(agent): unify models and validate OpenCode providers

Generate chat, task and learning models from agent-models.json.
Use WaterNetwork fast/expert models with 272k context and validate
upstream names before readiness. Add an isolated model check command
with signal-safe cleanup and plugin, Skill and MCP management docs.

Verified in isolation: type checks, 26 focused tests and both model
catalog checks; no model inference requests.

Dockerfile

@@ -62,7 +62,7 @@ WORKDIR /app
 COPY --from=deps /app/node_modules ./node_modules
 COPY --from=deps /app/.opencode/node_modules ./.opencode/node_modules
 COPY package.json bun.lock ./
-COPY tsconfig.json opencode.json README.md .gitignore ./
+COPY tsconfig.json opencode.json agent-models.json README.md .gitignore ./
 COPY scripts ./scripts
 COPY src ./src
 COPY .opencode ./.opencode