fix: orphaned approvals, token inflation, reasoning fields, memfs redis dep

[IN TESTING — self-hosted 0.16.6, Kimi-K2.5 via Synthetic Direct]

Four independent fixes that landed together on this stack:

helpers.py — skip PendingApprovalError when the associated run is already
cancelled or failed. Stale approvals from interrupted runs were blocking all
subsequent messages on that conversation. Now checks run status before raising;
falls back to raising on lookup failure (conservative).

letta_agent_v3.py — use prompt_tokens not total_tokens for context window
estimate. total_tokens inflated the estimate by including completion tokens,
triggering premature compaction. This was causing context window resets mid-
conversation and is the root of the token inflation bug (see #3242).

openai_client.py (both build_request_data paths) — strip reasoning_content,
reasoning_content_signature, redacted_reasoning_content, omitted_reasoning_content
from message history before sending to inference backends. Fireworks and Synthetic
Direct reject these fields with 422/400 errors. exclude_none handles None values
but not actual text content from previous assistant turns.

block_manager_git.py — skip DB write when block value is unchanged. Reduces
unnecessary write amplification on every memfs sync cycle.

memfs_client_base.py — remove redis_client= kwarg from GitOperations init.
Dependency was removed upstream but the call site wasn't updated.

Dockerfile / compose files — context window and config updates for 220k limit.

letta/services/block_manager_git.py

@@ -109,7 +109,9 @@ class GitEnabledBlockManager(BlockManager):
             block = result.scalar_one_or_none()
 
             if block:
-                # Update existing block
+                # Update existing block only if content changed
+                if block.value == value:
+                    return block.to_pydantic()
                 block.value = value
                 if description is not None:
                     block.description = description