feat(store): add tines-store persistent append-only LogStore

Add the host-side std `tines-store` crate implementing the `tines_core::Store`
trait over a durable, append-only single-file log so a robot's memory survives
reboot.

- Log format: length-prefixed `[u32 LE][postcard]` records (Obs/Trim/Meta).
- On load the index is rebuilt by replaying the log, then every age is
  rebased to load time: elapsed time since the last persisted clock marker is
  folded into `age_ms` and `stored_at` reset to load `now`, so ages continue
  instead of freezing across a reboot.
- Persisted state: released-id set, `next_seq`, and a clock marker in a `Meta`
  record; dedupe to the oldest Obs and let the last event per id win so a
  re-inserted id survives a trim.
- Implements `next_seq` and `flush`; `trim` writes Trim records best-effort.
- Registered as a workspace member; std-only, `#![forbid(unsafe_code)]`.
- Adds persistence tests (append durability, rebase-on-load, released/seq
  persistence). Full gate (fmt, clippy, docs, tests, no_std thumb build) is green.

tines-store/src/lib.rs

@@ -0,0 +1,11 @@
+//! tines-store — persistent append-only `LogStore` backend.
+//!
+//! This crate is the host-side (std) persistence layer for tines. The `Store`
+//! trait, `TrimPolicy`, and `StoreError` live in `tines-core` (which stays
+//! `no_std` and I/O-free); everything durable lives here.
+
+#![forbid(unsafe_code)]
+
+pub mod log;
+
+pub use log::LogStore;