chore: retire the last dead paths and names from the consolidation

Nothing here changes what a tool computes; it changes where tools look.

- tools/re-capture: 33 censuses globbed /work/sylph_extract, a path that has
  existed nowhere since /work became a clone, so they matched nothing and
  printed empty results. They now resolve the disc through a new disc.py
  from $SYLPHEED_DISC and exit loudly without it (the #44 fix, generalised).
  Nine scripts that imported siblings from the retired Reborn checkout or an
  old session scratchpad now import from their own directory. unitgroup.py
  only needs the variable when --pak is not given.
- sylpheed-xex: the loader only ever uses the XEX2 retail key. The dead
  devkit key and a doc comment claiming a devkit fallback that does not
  exist are gone; Project Sylpheed is a retail XEX2, so no XEX1 key either.
- sylpheed-viewer: real_font_rasterizes looked for /tmp/sylph_extract and so
  always skipped. It reads $SYLPHEED_DISC now, and passes against the disc.
- Comments and docs that named xenia-rs, the Reborn repository or /work/*.pe
  as places to look now name sylpheed.db, Canary's ppc_context.h and the
  flat .pe; docs/re/README.md no longer says the native Canary build does not
  run.

Historical records keep their original paths: findings that were measured
against /work/xenia-rs/sylpheed.db still say so.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/sylpheed-ppc/examples/decode_table_check.rs

@@ -6,7 +6,7 @@
 //! or a mis-decode in our tables.
 //!
 //! ```text
-//! cargo run --release -p xenia-cpu --example decode_table_check -- <table.txt>
+//! cargo run --release -p sylpheed-ppc --example decode_table_check -- <table.txt>
 //! ```
 //! where each line is `0xWORD name`.
 use std::io::BufRead;

crates/sylpheed-viewer/src/iso_loader.rs

@@ -5542,12 +5542,16 @@ mod font_sample_tests {
     /// panicking (regression for the egui `set_fonts` crash).
     #[test]
     fn real_font_rasterizes() {
-        let pak = Path::new("/tmp/sylph_extract/dat/movie/eng.pak");
+        let Some(disc) = std::env::var_os("SYLPHEED_DISC") else {
+            eprintln!("SKIP: SYLPHEED_DISC not set");
+            return;
+        };
+        let pak = Path::new(&disc).join("dat/movie/eng.pak");
         if !pak.exists() {
-            eprintln!("SKIP: extract not present");
+            eprintln!("SKIP: {} not present", pak.display());
             return;
         }
-        let arc = sylpheed_formats::PakArchive::open(pak).unwrap();
+        let arc = sylpheed_formats::PakArchive::open(&pak).unwrap();
         let bytes = arc.read_by_hash(0x5cd0_fca6).unwrap().unwrap();
         assert!(sylpheed_formats::font::is_font(&bytes));
         let img = render_font_sample(&bytes, "The quick brown fox 0123", 34.0)

crates/sylpheed-xex/src/header.rs

@@ -32,7 +32,7 @@ pub struct Xex2SecurityInfo {
     pub load_address: u32,
     pub export_table_address: u32,
     pub image_flags: u32,
-    /// Encrypted session key (decrypted with retail/devkit key to get actual session key).
+    /// Encrypted session key (decrypted with the retail key to get the actual session key).
     pub aes_key: [u8; 16],
     pub page_descriptors: Vec<Xex2PageDescriptor>,
 }

crates/sylpheed-xex/src/loader.rs

@@ -493,14 +493,13 @@ fn load_basic_compressed(source: &[u8], info: &FileFormatInfo) -> io::Result<Vec
 }
 
 /// Xbox 360 retail AES key for XEX2 session key decryption.
+///
+/// The only key this loader needs: Project Sylpheed ships as a retail XEX2. The
+/// devkit (all-zero) and XEX1 keys that other loaders try are deliberately absent.
 const XEX2_RETAIL_KEY: [u8; 16] = [
     0x20, 0xB1, 0x85, 0xA5, 0x9D, 0x28, 0xFD, 0xC3, 0x40, 0x58, 0x3F, 0xBB, 0x08, 0x96, 0xBF, 0x91,
 ];
 
-/// Xbox 360 devkit AES key (all zeros).
-#[allow(dead_code)]
-const XEX2_DEVKIT_KEY: [u8; 16] = [0u8; 16];
-
 /// AES-128-CBC decryption with zero IV (matching Xbox 360 XEX decryption).
 #[tracing::instrument(skip_all, fields(bytes = input.len()))]
 fn aes_decrypt_cbc(key: &[u8; 16], input: &[u8]) -> Vec<u8> {
@@ -528,7 +527,6 @@ fn aes_decrypt_cbc(key: &[u8; 16], input: &[u8]) -> Vec<u8> {
 }
 
 /// Derive the session key by decrypting the XEX's aes_key field with the retail key.
-/// Falls back to devkit key if retail produces invalid results.
 fn derive_session_key(header: &Xex2Header) -> [u8; 16] {
     let sec = match &header.security_info {
         Some(s) => s,

crates/sylpheed-xexdb/tests/disasm_goldens.rs

@@ -1,10 +1,10 @@
-//! Analysis-side goldens: every row in the xenia-cpu fixtures must
+//! Analysis-side goldens: every row in the sylpheed-ppc fixtures must
 //! round-trip cleanly through the [`sylpheed_xexdb::ppc`] shim. This
 //! pins the shim's behaviour to the canonical `sylpheed_ppc::disasm::format`
 //! output so that any future refactor of the shim layer surfaces here.
 //!
 //! Loads the same JSON fixtures committed under
-//! `crates/xenia-cpu/tests/golden/`. No separate analysis-side fixture
+//! `crates/sylpheed-ppc/tests/golden/`. No separate analysis-side fixture
 //! files — the cpu canon is the source of truth.
 
 use std::path::PathBuf;