feat: scienting-math/1 sources and derived/math.jsonl; lode references; stress fixes

Math content may say its source is in scienting-math/1's canonical TeX (form,
in no hash); derived/math.jsonl holds papermath's tree, symbols and issues,
and the validator now checks derived files. A symbol annotation names its
symbol by key; lode claim references use lode's tag and pin syntax. The zip
reader refuses entries zipfile cannot read, and checkpoint lines end in LF only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017R7sgDNvUGWY2zFPCq2JH6

docs/overview.md

@@ -52,7 +52,7 @@ It appears inside hashed data and test vectors, and it is separate from the repo
 | Folder | Holds |
 | --- | --- |
 | [spec/](../spec/README.md) | The specification, in 24 chapters (00 to 23). Normative. |
-| [schemas/](../schemas/README.md) | 42 JSON (plain-text data format) Schemas for the files and records. |
+| [schemas/](../schemas/README.md) | 43 JSON (plain-text data format) Schemas for the files and records. |
 | [registry/](../registry/README.md) | The list of formats, the rule IDs a checker reports, download-stamp rules, and default rights requirements. |
 | [tools/](../tools/README.md) | How to run the reference commands: `paperspec check` checks everything, `paperspec build` rebuilds the fixtures and vectors, and `paperspec load` loads packages into SQLite. |
 | [src/paperspec/](../src/paperspec/) | The oracle, a compact implementation of every rule, which the other repositories of the project install as the Python package `paperspec`. |