chore(release): 0.0.3

Squash-merge lib-standardisation: adopt repo standards across packaging,
tooling, docs, and CI.

- standardize pyproject.toml (canonical packaging, lint config, extras, GSDFC pydoclint)
- add py.typed marker, modernize type hints and Google-style docstrings
- nest generated docs under docs/lib and docs/mcp; add hand-written wiki
- adopt standard Type A PyPI CI pipeline (tag==version guard + quality gate)
- promote generated CHANGELOG.md; bump version to 0.0.3

docs/lib/adapters/base.md

@@ -0,0 +1,3 @@
+# Base
+
+::: mail_intake.adapters.base

docs/lib/adapters/gmail.md

@@ -0,0 +1,3 @@
+# Gmail
+
+::: mail_intake.adapters.gmail

docs/lib/adapters/index.md

@@ -0,0 +1,3 @@
+# Adapters
+
+::: mail_intake.adapters