feat(lattice): add durable runtime stores

[mgazza]

Summary

• add exact filesystem CAS stores for fragment adapter state and compiled Lattice publications
• add a secret-free materializer checkpoint store with a separately durable monotonic fence allocator
• add a target-owned opaque journal with bounded bytes, revision/fence checks, and payload-hiding diagnostics
• use a strict versioned/tagged allowlist codec with integrity, type, size, depth, node and container bounds
• provide thread/process exclusion, private filesystem invariants, atomic replace, file/parent fsync, and exact post-replace readback

Scope

This persistence-only tranche is stacked on #4359.

It does not implement WholeConfigTarget, construct or drain the compiler, register a runtime component, touch COMPONENT_LIST, mutate live args/configuration, write apps.yaml or secrets.yaml, or wire any provider. The two new files have no production registration.

Validation

• complete targeted matrix: 125/125 on Python 3.9 and 125/125 on Python 3.14
• new focused durable-store suite: 6/6 per interpreter
• all existing autoconfig tests: 53/53 per interpreter
• existing fragment adapter suite: 25/25 per interpreter
• existing compiled publication suite: 19/19 per interpreter
• existing atomic materializer suite: 22/22 per interpreter
• targeted pre-commit: whitespace, EOF, Ruff, Black and CSpell
• git diff --cached --check
• GitNexus staged scope: MEDIUM, 72 symbols, four new internal persistence flows; no production compiler/runtime flow
• final independent correctness review: APPROVE

Safety invariants

• existing HIGH-reach persistence protocols are not modified
• missing state is distinct from corrupt/torn/oversized state
• every decoded object is reconstructed only from an explicit enum/dataclass allowlist and revalidates domain invariants
• bool, integer and float encodings are non-interchangeable
• CAS compares exact canonical state under a process/thread lock
• a fence is durably advanced before it is returned
• record and lock files must be current-euid, mode 0600, single-link regular files in a non-symlink, current-euid, non-group/world-writable directory
• zero/short writes, file fsync, parent fsync, replace ambiguity and exact-readback failures fail closed; restart can recover an exact landed replacement
• coordinator state retains digests and bounded opaque handles, not raw feedback/config secrets
• opaque target bytes are filesystem-protected rather than encrypted; their later schema remains target-owned
• persisted compiled publications are revalidated against compiler-equivalent target, topology,
  projection, readiness, field and provenance invariants before use
• provider-declared non-monotonic projection order is preserved while slot uniqueness and bounds
  remain enforced