docs: add operating manual, fix cross-references after doc restructure

- Commit CLAUDE.md + AGENTS.md so a fresh clone has the operating manual and
  the ABI/no-game-logic rules (trimmed of stale phase status; the personal
  pd_port path removed; points at the split docs).
- Sweep every stale doc reference across the tree after the restructure:
  PCPortResearch.md -> internals.md / dev/findings.md,
  PORT-LEARNINGS.md -> porting-notes.md,
  AGENT-WORKFLOW.md -> dev-process.md,
  docs/{GRAPHICS-BACKLOG,HANDOFF-ARCHIVE,GE-ENV-PROBES,LEVEL-*,TEXTURE-GLITCH-ANALYSIS,AUDIT-M6-*,AUDIO-PLAN}.md -> docs/dev/.
- Drop the superseded docs/PLAN-linear-level-sweep.md.
- docs/HANDOFF.md + docs/BACKLOG.md stay local-only (rolling working files);
  CLAUDE.md now handles their absence in a fresh clone.

CLAUDE.md

@@ -0,0 +1,66 @@
+# CLAUDE.md — GoldenEye 007 PC port
+
+This file auto-loads every session. It is the operating manual. The full
+rules are in `AGENTS.md` (imported below); this file adds the two
+checklists that were being skipped.
+
+@AGENTS.md
+
+## Doc load order — read deliberately, not everything
+
+Context is scarce. Load by tier; do not blind-read whole files.
+
+- **Tier 0 — always (auto-loaded):** `CLAUDE.md`, `AGENTS.md`. Nothing
+  else auto-loads.
+- **Tier 1 — every session start, read fully (both are short):**
+  `docs/HANDOFF.md` (current state + next task + environment — a rolling
+  local working file; may be absent in a fresh clone, in which case read
+  the README "Status" section instead),
+  `docs/porting-notes.md` (recurring bug classes).
+- **Tier 2 — on demand only, do NOT read start-to-finish:**
+  - `docs/internals.md` — architecture / RSP deltas / phased plan (§1–§10
+    of the old research doc). Read the section you need.
+  - `docs/dev/findings.md` — the `Dxx` finding log (§11 + §F + §H).
+    **Jump to a specific `Dxx` via the index at the top of §F.** Never
+    linear-read.
+  - `docs/dev/HANDOFF-ARCHIVE.md` — prior-session narrative (M-2…). Only
+    when tracing the history of one fix.
+  - `docs/dev-process.md` — before dispatching a subagent (also Tier 1
+    if you may dispatch this session).
+
+## Session preflight — do this in your FIRST few tool calls, before acting
+
+Having a concrete "next step" from the handoff is NOT license to skip this.
+
+1. Read the Tier 1 docs: `docs/HANDOFF.md` (immediate task, standing
+   procedure, environment gotchas) and `docs/porting-notes.md`
+   (recurring bug classes — you will re-derive catalogued bugs if you don't).
+2. Skim the README "Status" section for where the project stands.
+3. If you may dispatch a subagent this session, read `docs/dev-process.md`
+   NOW — not at dispatch time.
+
+## Dispatch preflight — EVERY Agent/Task spawn, no exceptions
+
+A subagent brief is INVALID and must not be sent unless it contains all of:
+
+- **FILES YOU MAY TOUCH** — disjoint from every other running agent.
+- **BUDGET** — `<= N build->run->inspect cycles` or `~M min`. Tight for
+  cheap-class bugs (truncations, off-by-ones); more room for structural ones
+  (matrix handedness, format specs). Escalate the default as the project hardens.
+- **ON EXPIRY** — stop, revert temp probes, write up what you have in
+  `docs/dev/findings.md` §F with an explicit confidence rating. A good
+  write-up of a half-solved bug is a deliverable, not a failure.
+- **KNOWN-GOOD / RULED OUT**, **CONSTRAINTS** (no game-logic changes;
+  ABI/layout/format only; `#ifdef PORT`; documented in §F), **REPORT** shape.
+- Instruction to read `docs/porting-notes.md` first and append any
+  generalisable quirk to it.
+
+Full template: `docs/dev-process.md` -> "Investigation-brief template".
+
+## Verification cadence (integrator / overseer)
+
+- **Per merged patch:** single-frame `GE_PCDUMP` capture diffed against the
+  committed golden baseline. Cheap. Do NOT gate every patch on a long soak.
+- **Per batch / integration checkpoint:** one 60s `-level_09` crash-free run.
+- Subagents on small disjoint subsystems (input, audio, saves, converters)
+  don't run the game — the overseer verifies.