Value opencode Go plan requests; per-duration cache prices; usage under answers

- opencode Go reports plan requests as cost 0 with the usage in allowance;
  ModelConfig::cost values them at the model's list prices (charged amounts
  and free requests stay as reported). Rows booked at 0 are valued once on
  start (idempotent).
- opencode's price list now has per-duration cache prices for some models
  ({"30m": ..., "12h": ...}): the shortest duration is used, also in tiers.
  Saving the provider's models failed with "untagged enum ModelEntry".
- Each answer shows tokens sent/received and the cost of the turn's requests
  (usage.cost filled when messages are saved and loaded).
- The chat title keeps a minimum width in a crowded top bar.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,23 @@
 All notable changes to CodeCraft. Versions follow [Semantic Versioning](https://semver.org/);
 until 1.0, minor versions may contain breaking changes.
 
+## [Unreleased]
+
+### Added
+
+- **Tokens and cost under every answer:** a small line under each answer of the model shows the
+  tokens sent/received and the cost of all requests of that turn.
+
+### Fixed
+
+- **Total cost of chats stopped growing (opencode Go):** opencode now reports plan requests as
+  "nothing charged" (cost 0, usage in `allowance`), and CodeCraft took the 0. Plan requests are
+  valued at the model's list prices again; earlier ones are corrected once on start.
+- **Saving opencode Go models failed after fetching prices** ("data did not match any variant of
+  untagged enum ModelEntry"): opencode lists cache prices per duration for some models
+  (`{"30m": …, "12h": …}`); the shortest duration is used now.
+- The chat title in the top bar no longer shrinks to a single letter when there are many chips.
+
 ## [v202611-00022] – 2026-11-11
 
 ### Added