R2: redesign session store with wire-format identity

Replace the single-session SessionManager seam with a directory-backed
catalog. session_manager.zig -> file_system_jsonl_store.zig; the old
machinery becomes internal SessionFile, and a new FileSystemJSONLStore
implements the redesigned SessionStore vtable (create/list/resolve/latest/
load/appendMessages) minting Session/SessionInfo handles.

Session logs now record wire-format provider identity
({api_style, base_url, model, reasoning}) instead of a single provider
string or CLI aliases; no api_key material is ever stored. Disk* content
types renamed Stored*; the rich audit-oriented write record is
PersistentMessage (in-memory Message + WireIdentity + provenance).

Agent.init now takes a Session; persist_provider/persist_model display
strings deleted (banner stays alias-based, resume picks default model).
Message.metadata round-trips. Dangling-prompt recovery dropped. CLI
migrated to the catalog store for run/resume/list. Clean break, no version
bump (old logs wiped).

1 files changed, 1 insertions, 1 deletions

diff --git a/libpanto/src/root.zig b/libpanto/src/root.zig
index b5fab1a..fb8c1df 100644
--- a/libpanto/src/root.zig
+++ b/libpanto/src/root.zig
@@ -10,7 +10,7 @@ pub const tool = @import("tool.zig");
 pub const tool_source = @import("tool_source.zig");
 pub const tool_registry = @import("tool_registry.zig");
 pub const session = @import("session.zig");
-pub const session_manager = @import("session_manager.zig");
+pub const session_manager = @import("file_system_jsonl_store.zig");
 pub const session_store = @import("session_store.zig");
 pub const null_store = @import("null_store.zig");
 pub const turn_persist = @import("turn_persist.zig");