chore: establish repository readiness baseline

[adihex]

Summary

• replace the stale provider-dependent quick start with a pinned, credential-free setup path and a verified architecture/package map
• document current runtime, ADP, orchestration, security, and release boundaries without presenting roadmap work as implemented
• add a prioritized flagship-readiness roadmap and repository-wide PR CI for build, tests, and ast-grep rules
• pin the mise toolchain, complete Docker's workspace manifest set, and fix two minimal type issues required by the current workspace build

Why

AgentX has a strong embeddable runtime and debugger-like control-plane concept, but the first-run path, public documentation, CI coverage, and release expectations did not accurately reflect the implementation. This establishes a trustworthy baseline before expanding features.

Validation

• mise exec -- pnpm build
• mise exec -- pnpm test — 55 files passed; 338 tests passed, 1 skipped
• mise exec -- pnpm ast-grep:test — 1 passed
• credential-free orchestrator demo completed with session.complete
• git diff --check

Known follow-up

• type-aware lint currently has 27 baseline errors
• configured global coverage thresholds are not yet met; this PR does not lower them
• the GitHub workflow needs its first Actions run
• Docker is unavailable in the audit orb, so the Docker target was not built there

Coordination

Open PRs #12, #13, and #14 do not overlap this change. PR #10 overlaps mise.toml and apps/zettel/src/frontend/components/SemanticVisualizer.tsx; the toolchain pins intentionally replace latest, while the one-line note-shape fix should be reconciled if #10 lands first.