docs: consolidate contract registry into spec/ + unify plans under docs/plan/

[hanwencheng]

What & why

Two related docs reorganizations requested by the operator.

1. Single canonical contract registry under docs/spec/

#171 had split the contract registry into a new top-level docs/contracts.md plus a docs/spec/deployed-contracts.md redirect stub. This re-unifies them:

• docs/spec/deployed-contracts.md is now the single canonical doc — ERC-4337 P-256 smart-account master (#164): plan + contracts E0–E8 + live mainnet infra & demo #171's superset (v2 stage-1 set + ERC-4337 Migrate master authority to an ERC-4337 P-256 smart-account (resolves §11 gating findings) #164 master infra + historical v1) plus the ABI-summary / re-deploy / "when this doc needs to change" sections that ERC-4337 P-256 smart-account master (#164): plan + contracts E0–E8 + live mainnet infra & demo #171 trimmed.
• Added an explicit prod-vs-test EVM deployer-wallet table (the original ask):

  Role	Deployer EVM address
  Local / prod deploy	0xdE644936D5B7d5d42032fd08bbA42Fbbfd6663Bc
  Test / CI	0x9FE9e6c208e9e75D2A19a5c2683127c33896F259

• The test contract set is documented faithfully as placeholder (tier-1 CI runs on ephemeral anvil; the env file itself says "replace post-deploy") — not presented as live.
• docs/contracts.md flipped to a redirect (so ERC-4337 P-256 smart-account master (#164): plan + contracts E0–E8 + live mainnet infra & demo #171's new links still resolve). Repointed arch.md §5, CLAUDE.md, operator-runbook-wire.md, and the erc4337 plan.

2. Unify plans under docs/plan/ (removed docs/spec/plans/)

Assessed every plan for outdated-ness, then consolidated:

• Active → docs/plan/: milestones-roadmap + execution-plan (canonical, referenced from arch.md/CLAUDE.md), ceo-plan, issue-103, issue-107-mcp-demo-runbook, issue-74-step-1c, issue-82-erc7730, issue-credential-storage-s3-oidc, phase-1-wire-onboarding, phase1-wire-harness-test-plan, v2-issues/.
• Shipped/outdated → docs/archived/: issue-64/, issue-107-mcp-server-phase1, issue-144, issue-74-dev-key-service, agent-initiated-pairing-method-a, design-spec, eng-review-test-plan.
• All 32 moves via git mv (history preserved); docs/plan/README.md index rewritten.

Reviewer notes

• ~50 references rewritten across docs, wiki, Rust doc-comments, Cargo.toml, harness/scripts, pm/, README — including relative plans/X.md links inside docs/spec/ and a full depth-correction pass (moving files up one dir level broke every ../ up-link; 106 links fixed semantically by resolving against the repo tree).
• Code changes are comment / doc-string only — no logic touched (verified: the only .rs/.toml edits are //!, ///, #, and one doc-URL string constant).
• Verification: a broken-link scan confirms zero broken links to any moved or contract file; the new contracts doc's 10 internal links all resolve.

Deferred (out of scope)

• ~30 links to development-stages.md are broken, but were already broken before this PR (that file was archived in a prior PR). Tracked separately.
• Moved-to-archived files' own internal cross-links are now stale from the depth shift — left frozen per the docs/archived/ "never read in normal dev" policy.

🤖 Generated with Claude Code