Bootstrap "group B" classes that are not hardcoded (TRef, TRefArray, TClonesArray, TMap, TExMap, TBtree, TStringLong, TQObject/TCanvas, bitset, deque, …)

[nsmith-]

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Bootstrap classes §5 "Group B: the classes streamer-driven reading gets wrong" lists the ROOT classes whose recorded streamer info is absent or does not describe their bytes, so a reader must hardcode them. These are missing from src/rootfilespec/bootstrap/__init__.py. Checklist (observations are from running rootfilespec on the spec fixtures under reference/root-io-spec/data/):

• TRef — References §3. serialization/references.root, ref-variants.root: Unknown type TRef (4 records)
• TRefArray — References §4
• ProcessID<n> key resolution — References §2. TProcessID itself reads (streamer-info driven, a TNamed payload), but nothing maps references to it; see TObject: fUniqueID is read signed and unmasked; pidf is never combined with fPidOffset or resolved to a ProcessID record #110
• TClonesArray — Collections §12 (two body encodings selected by fBits bit 12 kBypassStreamer). serialization/clones-array.root: Unknown type TClonesArray
• TMap — Containers §1 (needs Object references are never resolved: instance_refs is never populated and Ref(Some()) is returned #104 for shared values)
• TExMap — Containers §2
• TBtree — Containers §3 (class version 0: needs StreamHeader uses the fByteCount >= 6 heuristic to decide whether a checksum follows a version word of 0 #111). classes/containers.root: all three unknown
• TStringLong — Conventions §5.1.1 in 00-conventions.md (four-byte count). serialization/stringlong.root: Expected position 662 but got 178
• TQObject / TCanvas — TCanvas (a TQObject base occupies zero bytes). classes/canvas.root: TVirtualPad depends on TQObject which is missing
• std::bitset<N> — Collections §11 (count = number of bits, one byte per bit). src/rootfilespec/structutil.py:111-115 raises NotImplementedError
• std::deque — Collections §1/§11. src/rootfilespec/container.py:291-296 raises NotImplementedError
• TTreeIndex — TTree auxiliary classes §2 in 04-ttree/Auxiliary.md (the one class with no streamer info)
• TBranchClones — §13 of 04-ttree/TBranchElement.md
• THashList — not hardcoded and currently reads only by accident of An object slot's class record and the object's own frame are conflated (pointers to non-TObject classes desync) #105; add an explicit test

Covered elsewhere: TMatrixTSym → #73; TArrayL/TArrayL64 → #107.

Note Bootstrap §6 "The list cannot be closed": user classes can have hand-written streamers too (#69, #71), so the fallback of #98 / #74 matters as much as this list.

Severity / size: medium–high per class on files that contain them / S–M each; implement on demand, each with its spec fixture as the test vector.

Assisted-by: claude-code:claude-fable-5-1