chore: track all project map and index files

Add generated .pi-map.md and .pi-map.index.md files across the repository
so the project navigation maps are shared and versioned. These artifacts
are maintained by project_map_init/patch/validate and must be kept in
sync with source edits.

Note: .cache/ remains ignored (added in previous commit).

docs/architecture/decisions/.pi-map.index.md

@@ -0,0 +1,20 @@
+# docs/architecture/decisions (index)
+dir: docs/architecture/decisions
+
+## role
+Documents key architectural decisions for the project, providing rationale and context for technology choices around authentication and database access patterns.
+## parent
+index: docs/architecture/.pi-map.index.md
+map: docs/architecture/.pi-map.md
+## children
+-
+## files
+- adr-001-session-auth.md
+- adr-002-async-sqlalchemy.md
+## links
+index: docs/architecture/decisions/.pi-map.index.md
+map: docs/architecture/decisions/.pi-map.md
+## workflows
+-
+## dirty
+-

docs/architecture/decisions/.pi-map.md

@@ -0,0 +1,20 @@
+# docs/architecture/decisions
+dir: docs/architecture/decisions
+
+index: docs/architecture/decisions/.pi-map.index.md
+
+## role
+Documents key architectural decisions for the project, providing rationale and context for technology choices around authentication and database access patterns.
+## files
+- adr-001-session-auth.md | Documents the architectural decision to use session-based authentication with HMAC-signed httpOnly cookies for OAuth2 flow instead of JWT alternatives | dep: Authentik, Traefik, OAuth2, HMAC-SHA256
+- adr-002-async-sqlalchemy.md | Architecture decision record documenting the choice to use SQLAlchemy 2.0 with async PostgreSQL via asyncpg for an async-capable Python application | dep: SQLAlchemy 2.0, PostgreSQL, asyncpg, Alembic
+## arch
+Lightweight ADR (Architecture Decision Record) pattern using Markdown files with sequential numbering, each capturing context, decision, consequences, and alternatives considered for major technical choices.
+## tags
+adr, async, session, sqlalchemy, decision, hmac, oauth2, 001
+## symbols
+-
+## workflows
+-
+## dirty
+-