Add memory provider

[fivetran-davefowler]

Summary

Adds a tool-agnostic memory provider for durable agent-facing data semantics.

• Adds agents-schema memory --memory-file memory.yml
• Writes AGENTS.MEMORY and AGENTS.MEMORY_ANCHOR
• Registers the memory provider in AGENTS.ROOT
• Keeps the core schema small: memory id/kind/title/content/source/confidence plus anchors for table, column, relationship, and metric retrieval
• Does not repeat a row-level provider in AGENTS.MEMORY; the table family is already the memory provider, and multi-tool provenance belongs in source
• Documents memory as an aggregator/summarizer layer over richer providers like LookML, dbt, OSI, catalogs, and reviewed agent discoveries
• Documents canonical YAML plus a compact project memories.yaml authoring shape that maps into the canonical tables
• Adds a Mermaid schema DAG for the memory tables and anchor targets
• Validates YAML strictly: unknown fields, bad scalar types, duplicate memories, duplicate anchors, invalid anchor types, and missing locators fail fast

Review

Dataface reviewer pass: APPROVED before the later schema simplification. The latest change is a narrower schema shape and passing tests.

Verification

uv run python -m unittest discover -s tests
Ran 18 tests
OK

git diff --check

[fivetran-davefowler]

Superseded by #13 — the notes_provider branch was renamed to memory-provider, which closed this PR. #13 has the same work plus the review refinements (float confidence, inline relationship anchors, OSI ai_context framing, tighter validation, and the missing workflow/setup files).