fix(history): count compressed rollouts, read each file once, degrade an unreadable parent

Codex's local_thread_store_compression rewrites cold rollouts to
*.jsonl.zst, which the store scan skipped without a trace. Each one is now
counted in compressedFiles (complete: false), skipped only when its plain
.jsonl sibling exists, as Codex's own discovery does, and a lookup that
misses names the compressed file whose name carries the wanted id. A
Zstandard file given to --file, or sitting in the store under a .jsonl
name, is recognised by its magic number.

Each selected rollout is parsed once into every view later needed of it,
so a legacy copy's boundary proof reuses the parent's own read instead of
charging it to --scan-bytes a second time (and counting its malformed or
inherited records twice).

A parent read that fails for any reason other than a budget now leaves
the boundary unproven (cut at the last candidate, unverifiedPrefixes,
complete: false) instead of failing a child whose own file is intact. A
budget error still fails the read.

--max-bytes is validated before the first file is read, next to the
other budgets, and every budget flag accepts plain decimal integers only.

.changeset/offline-codex-history.md

@@ -2,4 +2,4 @@
 'aicodeman': minor
 ---
 
-Add offline `codeman history read` for saved Codex transcripts by file, native session ID, or conversation family (spawned sub-agents and forks included), with whole-turn topic and UTC date filters. A forked or spawned thread's copy of its parent's history is dropped, so every record belongs to the thread that wrote it. Store attribution has its own budget (`--metadata-bytes`), separate from the transcript budget (`--scan-bytes`), and every bound is raisable (`--max-entries` too), so id lookups keep working on stores of thousands of rollouts. A store file that cannot be attributed, an unreadable directory, or a rollout a running Codex is still appending to no longer fails the lookup; each is reported through `complete: false`. Assistant records carry Codex's own phase and user records none. The Past Sessions scanner and the offline reader now share one Codex rollout format module, including the injected-context rule.
+Add offline `codeman history read` for saved Codex transcripts by file, native session ID, or conversation family (spawned sub-agents and forks included), with whole-turn topic and UTC date filters. A forked or spawned thread's copy of its parent's history is dropped, so every record belongs to the thread that wrote it. Store attribution has its own budget (`--metadata-bytes`), separate from the transcript budget (`--scan-bytes`), and every bound is raisable (`--max-entries` too), so id lookups keep working on stores of thousands of rollouts. A store file that cannot be attributed, an unreadable directory, or a rollout a running Codex is still appending to no longer fails the lookup; each is reported through `complete: false`, as is a Codex rollout compressed to `.jsonl.zst` (counted in `compressedFiles` and named when a lookup misses). A parent file read to prove where a forked copy ends is charged to `--scan-bytes` once, and a parent that cannot be read leaves that boundary unproven instead of failing the child. Assistant records carry Codex's own phase and user records none. The Past Sessions scanner and the offline reader now share one Codex rollout format module, including the injected-context rule.