docs(changelog): add Unreleased entries for deep-scan fixes

Five correctness and UX fixes: Gemini sticky truncation, shell wire
handoff for budget/stuck messages, dark-theme ptk hex parity,
non-review agent summary preview, and required_mcp_servers type filter.

Author: elkaix

CHANGELOG.md

@@ -15,6 +15,12 @@ GitHub Releases page; `0.8.0` is the new starting line.
 
 ## Unreleased
 
+- **Gemini finish_reason is now sticky once truncation is detected.** A second candidate with any non-`MAX_TOKENS` finish reason no longer overwrites a previously captured `"length"` signal at either the streaming or non-streaming path in the Google GenAI provider.
+- **Budget-exhausted and stuck-loop messages are now visible in the shell.** Both handoff messages were appended to context but never sent to the wire, so the interactive shell showed no feedback when a spend ceiling or stuck-loop exit fired. Both now emit a `TextPart` wire event so the message appears in the shell.
+- **Dark-theme prompt_toolkit border colors now match the TUI token constants.** Six stale slate hex values in `_PROMPT_STYLE_DARK` diverged from the current `border` and `border_muted` token values; they are now in sync and a parity test binds them going forward.
+- **Non-review successful agents now show a summary preview in the agent tree.** Completed subagents with a `summary_preview` now display a dim preview line in the RunAgents tree renderer (review runs continue to use the findings table instead).
+- **Non-string values in `required_mcp_servers` YAML are silently dropped.** Integers, booleans, and `null` entries were previously coerced to strings (`"1"`, `"False"`, `"None"`), creating permanently unsatisfiable MCP server names. Only actual string entries are now retained.
+
 - **Fixed MiniMax token-plan `/usage` accuracy.** The token-plan response now meters by
   percentage (the count fields are 0) and reports reset times in milliseconds; the adapter was
   reading the zero counts (showing "0 requests used") and treating milliseconds as seconds