chore: scaffold aura workspace and wire the skills dev-cycle

Cargo workspace aura-core -> aura-engine -> aura-cli (bin `aura`) plus nodes/ for hot-reloadable cdylib node crates. Crate bodies are intentionally API-free; types arrive from the first spec. Adds the skills profile (.claude/dev-cycle-profile.yml), the project CLAUDE.md with the eight domain invariants, and the design-ledger skeleton.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

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+# aura — project rules
+
+aura is a "game engine for traders": a Rust framework **and** a playground to
+author trading nodes, backtest them deterministically and massively in parallel,
+compose them fractally, validate them (sweep / Monte-Carlo / walk-forward), and
+freeze a validated strategy into a standalone bot with a broker connection.
+
+This file is the project sittenkodex. It imports the universal discipline from
+`~/dev/skills/templates/CLAUDE.md.fragment` and adds aura's domain invariants.
+The full architecture lives in the design ledger (`docs/design/`) and the specs
+(`docs/specs/`), not here.
+
+## Roles
+
+I am the **orchestrator**, not the implementer. The skills-plugin agents are my
+workers: I plan, design, decide, and integrate; they implement, refactor, test,
+and diagnose. Trivial mechanical edits I may do directly; anything needing broad
+reading or judgement goes to an agent. Agent reports describe intent, not
+outcome — I verify the diff and the test output myself before committing.
+
+## Commit discipline and main-branch sanctity
+
+- **Only the orchestrator commits.** No skill agent runs `git commit`; agents
+  leave their output as unstaged working-tree changes for me to inspect and shape
+  into commits.
+- **main HEAD is sacrosanct.** No `git reset`/`git revert` on main. main moves
+  forward only via my commits. Wrong agent output is discarded with
+  `git checkout -- <paths>`/`git stash`; a bad landing is fixed forward, never
+  rewound.
+- When a commit closes a Gitea issue, reference it in the body: `closes #N`
+  (or `refs #N` for non-final work).
+
+## Design rationale ≠ implementation effort
+
+Design choices are justified by substance — semantics, structural fit, what the
+design permits vs forbids, compositional clarity, future-proofing. Implementation
+effort ("approach A touches 250 sites, B touches 1") is an observation about the
+current code, not a rationale. Effort is at most a named tiebreaker after
+substantive reasons tie.
+
+## Bug fixes — TDD, always
+
+Bug fixes are RED-first and autonomous: the failing test exists in the working
+tree before any fix. The `debug` skill is mandatory for any observable
+misbehaviour (failing test, panic, wrong output).
+
+## Domain invariants (load-bearing — never silently violate)
+
+These are the contracts the whole design rests on. A change that breaks one is a
+design decision, not a refactor, and belongs in the ledger.
+
+1. **Determinism.** A backtest is a deterministic, synchronous, non-concurrent
+   event loop that reaches a unique state after each input tick. Same input →
+   same run, reproducibly. Two backtests are fully disjoint → concurrently
+   executable without locking. Parallelism is *across* sims, never within one.
+2. **Causality / no look-ahead.** A node sees only the past. Look-ahead is made
+   structurally impossible (read-only input windows that end at the cursor;
+   resamplers emit a bar only once it is complete), not merely discouraged.
+3. **One merge, at ingestion only.** Heterogeneous timestamped sources are
+   k-way-merged into a single chronological cycle stream at the ingestion
+   boundary. There is no merge / as-of join inside the graph.
+4. **The four scalar base types, streamed as SoA.** Only `i64`, `f64`, `bool`,
+   `timestamp` are streamed, as columnar Structure-of-Arrays. Composite streams
+   (e.g. OHLCV) are bundles of base columns. Non-scalars (String, Records,
+   tables, calendars) exist as metadata beside the hot path, never in it.
+5. **Acyclic dataflow.** The graph is a DAG; the only feedback path is an
+   explicit delay/state node (the RTL "register"). The "cycle" of the research
+   workflow is not a dataflow cycle.
+6. **Record-then-replay determinism boundary.** Anything non-deterministic,
+   external, or slow (LLM news agents, web sources) is materialized into a
+   recorded, timestamped stream *before* it enters the engine. The sim never
+   makes a live external call mid-replay. (See `~/.claude/CLAUDE.md` for the
+   IONOS consent rule: external LLM calls happen at the recording/live-source
+   edge, with explicit per-session consent, never inside a backtest.)
+7. **The broker is part of the strategy.** The broker node is fixed in a
+   strategy and identical in sim and live (one accounting path → one equity
+   curve shape). "Same strategy, different broker" = swap the broker *profile*
+   it is parameterized with. Live order-routing/reconciliation is an external
+   adapter outside the strategy graph.
+8. **Deploy artifacts are frozen.** Hot-reload (cdylib) is an authoring-loop
+   tool only. The live bot is a statically-linked, versioned, frozen artifact —
+   never hot-swapped (audit trail: this bot = this commit).