M0: repo scaffold, backend skeleton, schema + migrations, dev compose, docs

- Apache-2.0, README, CONTRIBUTING, CODE_OF_CONDUCT, SECURITY, issue templates
- FastAPI app with /api/v1 healthz/readyz/system-status (honest AI disclosure)
- Full SQLAlchemy schema (users, devices, refresh tokens, recordings, assets,
  upload sessions, transcripts, summaries, tags, jobs, exports) + Alembic
  migrations incl. Postgres FTS tsvector columns
- Settings via SHONAR_* env only; local + S3 storage abstraction with
  path-traversal-safe keys
- Docker dev compose (postgres+redis, 127.0.0.1-only); CI workflow; scripts
- shared/openapi.json contract generated from app

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,17 @@
+---
+name: Feature request
+about: Suggest an idea for S.H.O.N.A.R.
+title: "[FEATURE] "
+labels: enhancement
+---
+
+## Problem statement
+What problem does this solve for self-hosted voice-note users?
+
+## Proposed solution
+
+## Privacy impact
+Does this touch audio, transcripts, network, or AI providers? How is it
+disclosed to the user?
+
+## Alternatives considered