refactor: make src/llm/ self-contained for crate extraction (#767)

* refactor: make src/llm/ self-contained for crate extraction

Move LlmError, LLM config types, and OAuth callback helpers into
src/llm/ so the module has zero `use crate::` imports outside of
crate::llm. This prepares the module for extraction into a standalone
workspace crate.

- Move LlmError enum from src/error.rs to src/llm/error.rs
- Move LlmConfig, NearAiConfig, RegistryProviderConfig, BedrockConfig,
  CacheRetention, OAUTH_PLACEHOLDER from src/config/llm.rs to
  src/llm/config.rs
- Move OAuth callback utilities (callback_url, bind_callback_listener,
  wait_for_callback, landing_html, etc.) from src/cli/oauth_defaults.rs
  to src/llm/oauth_helpers.rs
- Remove session.rs dependency on crate::bootstrap (inline default path)
- Add cache_retention field to RegistryProviderConfig, resolve from env
  in config/llm.rs instead of reading env var in llm/mod.rs
- Add Check 6 to scripts/check-boundaries.sh enforcing LLM isolation
- All original locations re-export for backward compatibility

[skip-regression-check]

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* style: fix formatting

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address PR #767 review — session path bug and boundary check

1. Fix SessionConfig::default() usage in setup wizard: the fallback at
   wizard.rs:995 now constructs SessionConfig with the real
   default_session_path() instead of a relative "session.json", which
   would write auth tokens to the CWD instead of ~/.ironclaw/.

2. Widen check-boundaries.sh Check 6 to catch all `crate::` references
   (not just `use crate::` imports). Pre-existing inline references
   (16 occurrences) are reported as warnings; only new `use crate::`
   imports are hard violations.

[skip-regression-check]

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address PR #767 review and audit findings in src/llm/

PR review fixes:
- Reject wildcard addresses (0.0.0.0, ::) in OAuth callback listener
  to prevent session token exposure on all interfaces
- Fix boundary check comment-stripping that could hide real violations
  (use sed to strip inline comments before matching)

Audit fixes:
- Fix UTF-8 byte-index slicing panic in recording.rs hint extraction
- Add effective_model_name() delegation to RetryProvider and
  SmartRoutingProvider for consistency with other wrappers
- Add calculate_cost() delegation to CachedProvider and RecordingLlm
- Deduplicate retry loop logic in RetryProvider via generic helper
- Replace hardcoded /tmp path in recording tests with tempfile

Co-Authored-By: Claude Opus 4.6 <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 <[email protected]>

src/cli/doctor.rs

@@ -107,7 +107,7 @@ enum CheckResult {
 
 async fn check_nearai_session() -> CheckResult {
     // Check if session file exists
-    let session_path = crate::llm::session::default_session_path();
+    let session_path = crate::config::llm::default_session_path();
     if !session_path.exists() {
         // Check for API key mode
         if std::env::var("NEARAI_API_KEY").is_ok() {