feat(baton): batch inheritance — nearest declaration: ledger line, AILOG, Charter (#428)

[montfort]

Closes #428.

The ratification (#332 §3) put a batch's declaration on a - **Work verb**: ledger line. The AILOG template and the Track C kit put it in the AILOG frontmatter, and read_batches read neither, so every batch came out undeclared. This PR implements one contract that gives each existing slot a role (maintainer's decision, AIDEC-2026-09-17-001).

Rule: nearest declaration

A batch takes the first of these that declares a verb:

1. its own ledger line - **Work verb**: (and optionally - **Design provenance**:), the override for a heterogeneous batch;
2. the AILOG's frontmatter, the homogeneous default for its batches (the slot the template already ships);
3. the Charter(s) whose ledger this AILOG is, resolved exactly as straymark charter batch-complete does (originating_ailogs[0], else execution_ailogs[0]), when they all agree. This is the same agreement rule fix(baton): inherit task declarations from explicit Charter origins (#427) #430 uses for tasks.

Otherwise the batch stays undeclared.

• Unit semantics. An override replaces the whole declaration: a verb line without provenance does not inherit the parent's upstream, and a provenance line alone declares nothing.
• Unreadable sources. An unreadable AILOG frontmatter blocks inheritance for its batches, though their own lines still apply. An unreadable Charter blocks only Charter-level inheritance, and the CLI note now covers --granularity batch.
• Live text only. HTML comments, fenced blocks and lines after another heading never declare.
• Exact IDs. AILOG ids compare on the CLI's five-segment key, so …-001b ≠ …-001, and a slugged id resolves.

Refactor

• The parent index (CharterOrigin + ledger_ailog, ailog_key) and agreed() are shared by tasks and batches.
• task_inheritance_blockers becomes inheritance_blockers.

Impact (read-only, git status unchanged)

Corpus	Batches classified (all undeclared before)	Source
Sentinel	22	Ledger AILOGs of Charters 54 (operate), 55 (implement/new) and two more
LNXDrive	7	Charter 02 through its ledger AILOG
Estoa	8	AILOG frontmatter

Spot-checked against the source AILOGs and Charters.

Validation

• cargo test -p straymark-baton --locked: 112 passed. The 9 new cases are in tests/batch_inheritance.rs; 8 of them fail before the change (the ninth is a negative case).
• cargo clippy -p straymark-baton --all-targets --locked -- -D warnings is clean. straymark validate reports 0 errors.
• Ratification §3 and the Track C kit now describe the same contract. AILOG: AILOG-2026-09-17-004.

Heads-up: this PR and #436 both edit adjacent rows of the Track C kit table. Whichever merges second needs a one-line rebase, which I will do.

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