chore: add migration/ bundle for cross-machine setup

Bundles state that lives OUTSIDE the xenia-rs repo so a fresh clone on
another machine can be brought up to identical configuration via
migration/setup.sh:

  - claude-memory/             ~/.claude/projects/-home-fabi-RE-Project-Sylpheed/memory/
                               (103 files, 1.1 MB - MEMORY.md + every
                                project_xenia_rs_*.md from audits
                                addis_signext through audit-058)
  - project-root/dot-claude/   <project-root>/.claude/settings.json
                               (Stop hook + permissions)
  - project-root/ppc-manual/   <project-root>/ppc-manual/
                               (PowerPC reference docs, 397 files, 3.7 MB)
  - project-root/run-canary.sh <project-root>/run-canary.sh
  - README.md                  Human-readable setup checklist
  - setup.sh                   Idempotent installer (also reclones
                               xenia-canary at pinned HEAD 6de80dffe)
  - MANIFEST.md                Per-file mapping + per-file-not-bundled
                               restoration recipe

Excluded from bundle (not shippable via git):
  - Sylpheed ISO (7.8 GB; copyright; manual copy required)
  - sylpheed.db (395 MB; regenerable from XEX via analysis tooling)
  - target/ build artifacts (rebuild on target)
  - audit-runs probe firehoses (.log/.stdout/.stderr ~11 GB; rerun if needed)
  - audit-runs memory dumps (.bin ~4.5 GB; rerun audit-026/027/029 if needed)
  - xenia-canary checkout (setup.sh reclones from
    git.mc02.dev/fabi/Xenia-Canary.git at HEAD 6de80dffe)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

migration/project-root/ppc-manual/alu/mulldx.md

@@ -0,0 +1,130 @@
+# `mulldx` — Multiply Low Doubleword
+
+> **Category:** [Integer ALU](../categories/alu.md) · **Form:** [XO](../forms/XO.md) · **Opcode:** `0x7c0001d2`
+
+<!-- GENERATED: BEGIN -->
+
+## Assembler Mnemonics
+
+| Mnemonic | XML entry | Flags | Description |
+| --- | --- | --- | --- |
+| `mulld` | `mulldx` | — | Multiply Low Doubleword |
+| `mulldo` | `mulldx` | OE=1 | Multiply Low Doubleword |
+| `mulld.` | `mulldx` | Rc=1 | Multiply Low Doubleword |
+| `mulldo.` | `mulldx` | OE=1, Rc=1 | Multiply Low Doubleword |
+
+## Syntax
+
+```asm
+mulld[OE][Rc] [RD], [RA], [RB]
+```
+
+## Encoding
+
+### `mulldx` — form `XO`
+
+- **Opcode word:** `0x7c0001d2`
+- **Primary opcode (bits 0–5):** `31`
+- **Extended opcode:** `233`
+- **Synchronising:** no
+
+| Bits | Field | Meaning |
+| --- | --- | --- |
+| 0–5 | `OPCD` | primary opcode (31) |
+| 6–10 | `RT` | destination GPR |
+| 11–15 | `RA` | source A |
+| 16–20 | `RB` | source B |
+| 21 | `OE` | overflow-enable flag |
+| 22–30 | `XO` | extended opcode (9 bits) |
+| 31 | `Rc` | record-form flag |
+
+## Operands
+
+| Field | Role | Description |
+| --- | --- | --- |
+| `RA` | mulldx: read | Source GPR (`r0`–`r31`). |
+| `RB` | mulldx: read | Source GPR. |
+| `RD` | mulldx: write | Destination GPR. |
+| `CR` | mulldx: write (conditional) | Condition-register update. When `Rc=1`, CR field 0 (or CR6 for vector compares, CR1 for FPU) is updated from the result. |
+| `OE` | mulldx: write (conditional) | Overflow-enable bit. When 1, the instruction updates `XER[OV]` and stickies `XER[SO]` on signed overflow. |
+
+## Register Effects
+
+### `mulldx`
+
+- **Reads (always):** `RA`, `RB`
+- **Reads (conditional):** _none_
+- **Writes (always):** `RD`
+- **Writes (conditional):** `CR`, `OE`
+
+## Status-Register Effects
+
+- `mulldx`: **CR0** ← signed-compare(result, 0) with `SO ← XER[SO]`, when `Rc=1`.; **XER[OV]** ← signed-overflow(result); **XER[SO]** stickies, when `OE=1`.
+
+## Operation (pseudocode)
+
+```
+RT <- ((RA) * (RB))[64:127]               ; low 64 of signed 64×64
+```
+
+## C Translation Example
+
+```c
+/* C translation: the xenia-rs interpreter arm below in           */
+/* Implementation References is the authoritative semantic        */
+/* snapshot. Translate it line-by-line:                            */
+/*   - ctx.gpr[N]  -> r[N]       (or f[]/v[] for FPRs/VRs)        */
+/*   - mem.read_u*/write_u* -> mem_read_u*_be / mem_write_u*_be   */
+/*   - ctx.update_cr_signed(fld, v) -> update_cr_signed(fld, v)   */
+/*   - ctx.xer_ca / xer_ov / xer_so -> xer.CA / xer.OV / xer.SO   */
+/* The Register Effects and Status-Register Effects tables above  */
+/* enumerate every side effect a faithful translation must emit.  */
+```
+
+## Implementation References
+
+**`mulldx`**
+- xenia-canary XML: [`tools/ppc-instructions.xml` — search for `mnem="mulldx"`](../../xenia-canary/tools/ppc-instructions.xml)
+- xenia-canary emit: [`src/xenia/cpu/ppc/ppc_emit_alu.cc:368`](../../xenia-canary/src/xenia/cpu/ppc/ppc_emit_alu.cc#L368)
+- xenia-rs opcode: [`crates/xenia-cpu/src/opcode.rs:57`](../../xenia-rs/crates/xenia-cpu/src/opcode.rs#L57)
+- xenia-rs decoder: [`crates/xenia-cpu/src/decoder.rs:872`](../../xenia-rs/crates/xenia-cpu/src/decoder.rs#L872)
+- xenia-rs interpreter: [`crates/xenia-cpu/src/interpreter.rs:433-444`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L433-L444)
+<details><summary>xenia-rs interpreter body (frozen snapshot)</summary>
+
+```rust
+        PpcOpcode::mulldx => {
+            let ra = ctx.gpr[instr.ra()] as i64;
+            let rb = ctx.gpr[instr.rb()] as i64;
+            ctx.gpr[instr.rd()] = ra.wrapping_mul(rb) as u64;
+            if instr.oe() {
+                overflow::apply(ctx, overflow::mulld_ov(ra, rb));
+            }
+            if instr.rc_bit() {
+                ctx.update_cr_signed(0, ctx.gpr[instr.rd()] as i64);
+            }
+            ctx.pc += 4;
+        }
+```
+</details>
+
+<!-- GENERATED: END -->
+
+## Special Cases & Edge Conditions
+
+- **Returns the low 64 bits of a signed 64×64 product.** Equivalent to `(int64_t)(RA * RB)` modulo `2^64`. Both operands are full 64-bit signed; no truncation on input.
+- **High bits silently lost.** The high 64 bits of the true product are discarded; pair with [`mulhdx`](mulhdx.md) (signed) or [`mulhdux`](mulhdux.md) (unsigned) to recover them.
+- **`OE=1` should set `XER[OV]`** when the 128-bit signed product cannot be represented in 64 bits — i.e. when `mulhd RA, RB` is not the sign-extension of `mulld RA, RB`. **Xenia-rs does not implement** `OE` ([`interpreter.rs:264`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L264) has no `oe()` branch).
+- **`Rc=1` CR0 update is correctly 64-bit.** [`interpreter.rs:269`](../../xenia-rs/crates/xenia-cpu/src/interpreter.rs#L269) uses `as i64` — full 64-bit signed compare. One of the few non-truncating CR0 sites in xenia-rs; means `mulld.` gives spec-correct CR0 even when the result has non-zero high 32 bits.
+- **Same instruction for signed and unsigned low halves.** Modular arithmetic is identical; only the high half (`mulhd` vs `mulhdu`) distinguishes the interpretations.
+- **Multi-cycle latency** — slowest of the ALU pipelines after divide.
+
+## Related Instructions
+
+- [`mulhdx`](mulhdx.md), [`mulhdux`](mulhdux.md) — signed/unsigned high halves of the same multiply.
+- [`mullwx`](mullwx.md) — 32-bit signed multiply (low 64).
+- [`mulli`](mulli.md) — D-form: `RT ← (RA[32:63]) × SIMM`.
+- [`divdx`](divdx.md), [`divdux`](divdux.md) — 64-bit divide, often paired with `mulld` for remainders.
+
+## IBM Reference
+
+- [AIX 7.3 — `mulld` (Multiply Low Doubleword)](https://www.ibm.com/docs/en/aix/7.3.0?topic=set-mulld-multiply-low-double-word-instruction)