chore: default DeepSeek model → v4-pro + bump to 0.12.0

- colibri-deepseek DEFAULT_MODEL: deepseek-chat → deepseek-v4-pro
  (matches zot's defaultModelForProvider('deepseek') = 'deepseek-v4-pro')
- Workspace version: 0.11.0 → 0.12.0

Cargo.toml

@@ -2,7 +2,7 @@
 members = ["crates/colibri-contracts", "crates/colibri-deepseek", "crates/colibri-runtime", "crates/colibri-glasspane", "crates/colibri-daemon", "crates/colibri-client", "crates/colibri-glasspane-tui", "crates/colibri-store", "crates/colibri-skills", "crates/colibri-mcp", "crates/colibri-vault", "crates/clawdie"]
 
 [workspace.package]
-version = "0.11.0"
+version = "0.12.0"
 
 [package]
 name = "colibri"

crates/colibri-deepseek/src/lib.rs

@@ -22,7 +22,7 @@ use serde_json::{json, Value};
 pub const DEFAULT_ENDPOINT: &str = "https://api.deepseek.com/chat/completions";
 // DeepSeek API model string (cache-capable). Distinct from our internal
 // `deepseek-v4-flash` alias; override with DEEPSEEK_MODEL.
-pub const DEFAULT_MODEL: &str = "deepseek-chat";
+pub const DEFAULT_MODEL: &str = "deepseek-v4-pro";
 
 // Deliberately long and byte-stable. Reasonix discipline: the immutable region
 // must not change between turns or the cache will not hit.