docs: add lesson descriptions and links to README

docs: update README to reference docs/ directory

docs: add reference documentation (architecture, memory, tools, sandbox)

chore: remove stale artifacts, rewrite README and SANDBOX docs

docs: rewrite lessons as 12-lesson building story

docs: improve lesson 01 to properly explain what an agent is

docs: rewrite lessons to match current agent architecture (15 lessons)

chore: update ISSUES.md from self-review

security: disable network access in sandbox by default

chore: update ISSUES.md from self-review

fix: use homedir for mkdir in saveEpisode to match TRACE_FILE path

feat: change to system-wide episodic memory

chore: update ISSUES.md from self-review

feat: add temporal grounding and recent context to memory recall

chore: update ISSUES.md from self-review