feat(P4-004): summarization pipeline — LLM + cron scheduling

Add SummarizationService that reads hot agent logs (>24h), groups by
session, calls a cheap LLM (gpt-4o-mini default, configurable via
SUMMARIZATION_MODEL) to extract key insights, stores them with
embeddings in the insights table, and transitions processed logs to
warm tier. Add CronService with node-cron for scheduled execution
(summarization every 6h, tier management daily at 3am). Tier
management promotes warm→cold (30d) and purges cold logs (90d).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pnpm-lock.yaml

@@ -113,6 +113,9 @@ importers:
       fastify:
         specifier: ^5.0.0
         version: 5.8.2
+      node-cron:
+        specifier: ^4.2.1
+        version: 4.2.1
       reflect-metadata:
         specifier: ^0.2.0
         version: 0.2.2
@@ -129,6 +132,9 @@ importers:
       '@types/node':
         specifier: ^22.0.0
         version: 22.19.15
+      '@types/node-cron':
+        specifier: ^3.0.11
+        version: 3.0.11
       '@types/uuid':
         specifier: ^10.0.0
         version: 10.0.0
@@ -2747,6 +2753,9 @@ packages:
   '@types/mysql@2.15.27':
     resolution: {integrity: sha512-YfWiV16IY0OeBfBCk8+hXKmdTKrKlwKN1MNKAPBu5JYxLwBEZl7QzeEpGnlZb3VMGJrrGmB84gXiH+ofs/TezA==}
 
+  '@types/node-cron@3.0.11':
+    resolution: {integrity: sha512-0ikrnug3/IyneSHqCBeslAhlK2aBfYek1fGo4bP4QnZPmiqSGRK+Oy7ZMisLWkesffJvQ1cqAcBnJC+8+nxIAg==}
+
   '@types/node@22.19.15':
     resolution: {integrity: sha512-F0R/h2+dsy5wJAUe3tAU6oqa2qbWY5TpNfL/RGmo1y38hiyO1w3x2jPtt76wmuaJI4DQnOBu21cNXQ2STIUUWg==}
 
@@ -4174,6 +4183,10 @@ packages:
       sass:
         optional: true
 
+  node-cron@4.2.1:
+    resolution: {integrity: sha512-lgimEHPE/QDgFlywTd8yTR61ptugX3Qer29efeyWw2rv259HtGBNn1vZVmp8lB9uo9wC0t/AT4iGqXxia+CJFg==}
+    engines: {node: '>=6.0.0'}
+
   node-domexception@1.0.0:
     resolution: {integrity: sha512-/jKZoMpw0F8GRwl4/eLROPA3cfcXtLApP0QzLmUT/HuPCZWyB7IY9ZrMeKw2O/nFIqPQB3PVM9aYm0F312AXDQ==}
     engines: {node: '>=10.5.0'}
@@ -7548,6 +7561,8 @@ snapshots:
     dependencies:
       '@types/node': 22.19.15
 
+  '@types/node-cron@3.0.11': {}
+
   '@types/node@22.19.15':
     dependencies:
       undici-types: 6.21.0
@@ -9001,6 +9016,8 @@ snapshots:
       - '@babel/core'
       - babel-plugin-macros
 
+  node-cron@4.2.1: {}
+
   node-domexception@1.0.0: {}
 
   node-fetch@3.3.2: