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

fixtures/README.md

@@ -25,7 +25,7 @@ A conforming reader accepts each one and recomputes every hash it contains.
 
 | Package | What it is for |
 | --- | --- |
-| `packages/hale2026harmonic/` | The main example, followed step by step in [the walkthrough](../docs/walkthrough.md): a chemistry paper that was read once with mistakes and then fixed by twelve corrections. It has a table with two levels of column headers and grouped rows, an equation inside a sentence, a footnote, a figure with text inside its panels and a real image, references, legacy aliases, boxes on fingerprinted pages, receipts in every state (counting, partly invalidated, spot-checked, revoked and suspended), the roster of public keys that checks their signatures, a dataset taken from the table, and derived MathML. |
+| `packages/hale2026harmonic/` | The main example, followed step by step in [the walkthrough](../docs/walkthrough.md): a chemistry paper that was read once with mistakes and then fixed by twelve corrections. It has a table with two levels of column headers and grouped rows, an equation inside a sentence, a footnote, a figure with text inside its panels and a real image, references, legacy aliases, boxes on fingerprinted pages, receipts in every state (counting, partly invalidated, spot-checked, revoked and suspended), the roster of public keys that checks their signatures, a dataset taken from the table, derived MathML, and the derived reading of three formulas in the math form `scienting-math/1`, one of which the form's tree cannot read ([spec/09 section 9.4](../spec/09-figures-tables-equations.md#94-the-math-form)). |
 | `packages/hale2026harmonic.checks-only/` | The same document prepared for sharing within the team: text withheld, every hash an HMAC (a hash computed under a secret key) under the team key. The team key is derived from the team secret in `keys/` ([spec/05](../spec/05-hashes.md), [spec/12 section 12.5](../spec/12-package.md#125-text-policies)). It shows how a team can share its checks on a paywalled paper without sharing the paper. |
 | `packages/okafor2025open/` | An open-access paper established from a JATS file (an XML format for journal articles) and a PDF that agree, so every leaf is at fidelity F2, corroborated by an independent witness. |
 | `packages/smithlab2027charges/` | A short draft written in Typst (a typesetting language). One of its sentences holds a cross-reference whose target is the address `hale2026harmonic#a4jrz2t`, a sentence of the main example. |
@@ -47,7 +47,7 @@ Each record is a single file, or a folder where a format needs several files.
 | `backend-docling.json`, `backend-examplevendor.json` | The code and weight licenses of a conversion tool and the conditions attached to them. |
 | `profile-acme.json`, `profile-smithlab.json` | What those conditions ask about a team: its purpose, its funding and whom it competes with. |
 | `roster.json` | The keys that may sign, the role of each key's holder in the team, and what each key may sign. Ana is the owner, so she may revoke anyone's receipt. |
-| `layer/` | A layer of annotations on the main example (`layer.json`, `annotations.jsonl`) and the receipt that confirms them (`receipt.json`). |
+| `layer/` | A layer of annotations on the main example (`layer.json`, `annotations.jsonl`) and the receipt that confirms them (`receipt.json`). Its claim link and its symbol name the claim `amber/k-bond` of lode's example store as lode references it, `lode:272XTX7C`, pinned at `lode:272XTX7C@02f47b`; the symbol names `K_r` by its key, `K_{r}`. |
 | `submissions/`, `grades/` | A student's answers to exercises in the layer, and the grader's result for each. |
 | `suspect.json` | A doubtful reading raised for review: the converter's reading of an exponent in the main example, before the first correction answered it. |
 | `qa-report.json` | Reviewer error bounds for a delivery that covers two of the main example's receipts, signed by the team's owner key. |