feat(register): modular @-import CLAUDE.md structure (ops-bridge pattern)

Replaces the monolithic project_claude_md.template with a directory of
7 focused rule files in scripts/project_rules/. register_project.sh now
generates .claude/rules/*.md + a thin CLAUDE.md index of @-imports,
matching the pattern established in ops-bridge.

Template files:
  claude-md.template          — 9-line @-import index
  repo-identity.template      — purpose, domain, slug, topic ID (machine-gen)
  session-protocol.template   — orient/inbox/workplans/brief/close (machine-gen)
  first-session.template      — bootstrap flow; delete once past FSP
  workplan-convention.template— prefix, location; delegates to global CLAUDE.md
  stack-and-commands.template — language/deps/commands (stub, manual)
  architecture.template       — design overview (stub, manual)
  repo-boundary.template      — what this repo does NOT own (stub, manual)

register_project.sh changes:
  - Generates .claude/rules/ from templates with variable substitution
  - Writes thin CLAUDE.md if none exists; appends suggestion comment if one does
  - Step 7: auto-registers this machine's local path via POST /repos/{slug}/paths/
  - project_claude_md.template deprecated to a redirect notice

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/project_rules/workplan-convention.template

@@ -0,0 +1,12 @@
+## Workplan Convention (ADR-001)
+
+File location: `workplans/{REPO_SLUG}-WP-NNNN-<slug>.md`
+ID prefix: `{WP_PREFIX}`
+
+Work items originate as files in this repo **before** being registered in the hub.
+
+Ecosystem todos from other agents arrive as `[repo:{REPO_SLUG}]` hub tasks —
+visible at session start. Pick one up by creating the workplan file, then registering
+the workstream.
+
+<!-- Ralph Loop rules and HEUREKA sequence: ~/.claude/CLAUDE.md — do not duplicate here -->