feat(remote): send read freshness headers for remote table consistency (#3439)

Closes client side work of #3370 

### Summary
- Plumbs `read_consistency_interval` from `ConnectBuilder` through
`RestfulLanceDbClient` so remote reads attach an
`x-lancedb-min-timestamp` freshness header. None = no header (default),
zero = "now", positive = `now - interval`.
- Adds per-table `FreshnessState` on `RemoteTable`: write responses
(`update`, `delete`, `merge_insert`, `add_columns`, `alter_columns`,
`drop_columns`) track the committed version, and the next read sends
`x-lancedb-min-version` so the server's cache honors read-your-write.
- `checkout(v)` / `checkout_tag(t)` / `checkout_latest()` / `restore()`
reset the freshness state appropriately; the validating `/describe/` and
tag-resolve requests are sent without freshness headers so they don't
carry stale state.
- Updates Rust, Python, and Node docstrings and calls out that stronger
consistency raises per-read latency and cost.

### Testing
- Unit tests cover default behavior, interval=0, positive interval,
checkout_latest baseline, min_version-after-write, checkout clears
state, and the two no-stale-header invariants on `checkout(v)` and
`checkout_tag(t)`.
- Ran smoke tests against local remote table to verify functionality

python/python/lancedb/__init__.py

@@ -94,7 +94,6 @@ def connect(
     host_override: str, optional
         The override url for LanceDB Cloud.
     read_consistency_interval: timedelta, default None
-        (For LanceDB OSS only)
         The interval at which to check for updates to the table from other
         processes. If None, then consistency is not checked. For performance
         reasons, this is the default. For strong consistency, set this to
@@ -104,6 +103,10 @@ def connect(
         the last check, then the table will be checked for updates. Note: this
         consistency only applies to read operations. Write operations are
         always consistent.
+
+        Stronger consistency is not free. The smaller the interval, the more
+        often each read pays the cost of checking for updates against object
+        storage, raising per-read latency and cost.
     client_config: ClientConfig or dict, optional
         Configuration options for the LanceDB Cloud HTTP client. If a dict, then
         the keys are the attributes of the ClientConfig class. If None, then the
@@ -217,6 +220,7 @@ def connect(
             request_thread_pool=request_thread_pool,
             client_config=client_config,
             storage_options=storage_options,
+            read_consistency_interval=read_consistency_interval,
             **kwargs,
         )
     _check_s3_bucket_with_dots(str(uri), storage_options)
@@ -343,7 +347,6 @@ async def connect_async(
     host_override: str, optional
         The override url for LanceDB Cloud.
     read_consistency_interval: timedelta, default None
-        (For LanceDB OSS only)
         The interval at which to check for updates to the table from other
         processes. If None, then consistency is not checked. For performance
         reasons, this is the default. For strong consistency, set this to
@@ -353,6 +356,10 @@ async def connect_async(
         the last check, then the table will be checked for updates. Note: this
         consistency only applies to read operations. Write operations are
         always consistent.
+
+        Stronger consistency is not free. The smaller the interval, the more
+        often each read pays the cost of checking for updates against object
+        storage, raising per-read latency and cost.
     client_config: ClientConfig or dict, optional
         Configuration options for the LanceDB Cloud HTTP client. If a dict, then
         the keys are the attributes of the ClientConfig class. If None, then the

python/python/lancedb/remote/db.py

@@ -50,6 +50,7 @@ class RemoteDBConnection(DBConnection):
         connection_timeout: Optional[float] = None,
         read_timeout: Optional[float] = None,
         storage_options: Optional[Dict[str, str]] = None,
+        read_consistency_interval: Optional[timedelta] = None,
     ):
         """Connect to a remote LanceDB database."""
         if isinstance(client_config, dict):
@@ -103,6 +104,7 @@ class RemoteDBConnection(DBConnection):
                 host_override=host_override,
                 client_config=client_config,
                 storage_options=storage_options,
+                read_consistency_interval=read_consistency_interval,
             )
         )