chore(release): v1.28.26 — internal restructuring for maintainability

No user-facing change. Eight of the largest source files split along their
natural seams into focused modules, every move verbatim with stable import
paths:

- mood analytics calculators (mood-tag-influence / mood-crosstab /
  mood-better-days / mood-patterns; hub 2229 → 770 lines)
- insight status-invalidation machinery (status-invalidation.ts)
- feature extraction (feature-blocks / signals-of-day)
- doctor report types + pure helpers (doctor-report-types /
  doctor-report-helpers; collector 1756 → 1002)
- Google Health mapping layer (mappers.ts; client 2153 → 1022, acyclic
  client → mappers with type-only back-imports)
- coach chat bubbles + read-aloud controls (chat-bubble / read-aloud;
  message-thread 1713 → 464)
- Telegram webhook handlers to lib (route 1307 → 92 — handler thin, logic in
  lib; rate-limit-before-secret ordering byte-identical)
- coach snapshot cache, series helpers and the four largest per-metric blocks
  (snapshot-cache / snapshot-series / snapshot-blocks; 2691 → 1896)

The glucose-panel-window structural test follows the moved alias; two unused
imports left by the feature split are removed.

docs/api/openapi.yaml

@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: HealthLog API
-  version: 1.28.25
+  version: 1.28.26
   description: >-
     Self-hosted personal-health-tracking PWA — public API surface for the iOS native client and external ingest.