docs(agent): vendor-neutral agent docs — AGENTS.md entry, agent/ SoT, .claude shims

The repo is maintained by agents from multiple vendors, so agent
instructions move out of vendor-specific locations into shared,
git-tracked markdown:

- AGENTS.md is the new entry point for any harness; CLAUDE.md becomes a
  symlink to it (Claude Code keeps working unchanged).
- Skill bodies relocate to agent/: VERIFICATION.md (the enforcement
  rules, ex .claude/skills/nomarchy), DELEGATION.md (capability tiers
  light/standard/frontier, scout/runner role contracts, token economy,
  parallel fan-out — consolidates the CLAUDE.md model table, LOOP.md's
  economy section, and skill §6.5 into one place; vendor model names
  survive only in the per-harness mapping table), THEME-DESIGN.md
  (ex .claude/skills/theme, which previously lacked frontmatter).
- .claude/ shrinks to a thin Claude Code adapter: settings, subagent
  defs, and skill shims that route into agent/.
- Maps updated: agent/README.md (instructions vs state vs adapters),
  docs/README.md, README.md layout tree.

Cleanup: stale old_distro .gitignore entry dropped (dir long gone);
local result*/__pycache__ artifacts removed; JOURNAL.md rotated (29
recent entries kept, 120 older moved to agent/JOURNAL-ARCHIVE.md,
rotation rule documented in the header).

Verification: V0 (docs/meta only) — nix flake check --no-build exit 0
with the tracked symlink; grep sweep confirms no vendor model names
outside DELEGATION.md's mapping table.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/README.md

@@ -19,9 +19,9 @@ tree for the same facts.
 
 | Path | Role |
 |------|------|
-| [../agent/README.md](../agent/README.md) | **Executable** agent loop state: BACKLOG, LOOP, MEMORY, … |
-| [../CLAUDE.md](../CLAUDE.md) | Agent entry point (any harness that reads it) |
-| [../.claude/](../.claude/) | Claude Code only: permissions + subagent defs |
+| [../AGENTS.md](../AGENTS.md) | Agent entry point, any vendor/harness (`CLAUDE.md` symlinks to it) |
+| [../agent/README.md](../agent/README.md) | Agent instructions + **executable** loop state: BACKLOG, LOOP, VERIFICATION, … |
+| [../.claude/](../.claude/) | Claude Code adapter only: permissions + subagent/skill shims |
 
 ## How work flows