fix(memory-lancedb): reject envelope metadata sludge

Summary:
- Strip memory-lancedb envelope and metadata sludge before auto-capture/recall, including pending history wrappers, current-message reply context, message-tool delivery hints, media annotations, and marker-free channel envelopes.
- Expose bundled chat-channel IDs/prefixes through the plugin SDK so sanitizer matching follows the channel catalog.
- Refactor cron tool schemas to fresh factory instances while preserving runtime nullable clears and provider-facing OpenAPI projection.

Verification:
- git diff --check origin/main...HEAD
- ./node_modules/.bin/oxfmt --check src/plugin-sdk/chat-channel-ids.ts src/plugin-sdk/chat-channel-ids.test.ts extensions/memory-lancedb/index.ts extensions/memory-lancedb/index.test.ts src/agents/tools/cron-tool.ts src/agents/tools/cron-tool.schema.test.ts
- pnpm plugin-sdk:api:check
- node scripts/run-vitest.mjs run src/plugin-sdk/chat-channel-ids.test.ts extensions/memory-lancedb src/agents/tools/cron-tool.schema.test.ts src/agents/tools/cron-tool.test.ts --reporter=dot
- pnpm lint:extensions --threads=8
- .agents/skills/autoreview/scripts/autoreview --mode branch --base origin/main
- GitHub checks on 62d1da1257: 139 pass, 0 pending, 0 fail, 22 skipped.

package.json

@@ -805,6 +805,10 @@
       "types": "./dist/plugin-sdk/bundled-channel-config-schema.d.ts",
       "default": "./dist/plugin-sdk/bundled-channel-config-schema.js"
     },
+    "./plugin-sdk/chat-channel-ids": {
+      "types": "./dist/plugin-sdk/chat-channel-ids.d.ts",
+      "default": "./dist/plugin-sdk/chat-channel-ids.js"
+    },
     "./plugin-sdk/channel-config-schema-legacy": {
       "types": "./dist/plugin-sdk/channel-config-schema-legacy.d.ts",
       "default": "./dist/plugin-sdk/channel-config-schema-legacy.js"