Initial import of LogDarioSeq baseline

Establishes version control for the personal Logseq DB fork before
starting the server-client architecture migration and domain features
described in docs/agent-guide and the approved implementation plan.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

cli/spec/platform/cli_platform.mli

@@ -0,0 +1,50 @@
+val hostname : unit -> string
+val argv : unit -> string array
+
+type login_callback_request = { target : string option }
+type login_callback_response = { status : int; body : string }
+
+type login_callback_server_error =
+  | Login_callback_timeout
+  | Login_callback_server_start_failed of string
+  | Login_callback_server_aborted of string
+
+val login_callback_server :
+  host:string ->
+  port:int ->
+  timeout_span:float ->
+  on_listen:(unit -> (unit, string) result Cli_effect.t) ->
+  handle_request:(login_callback_request -> login_callback_response * 'result) ->
+  ('result, login_callback_server_error) result Cli_effect.t
+
+module Symbols : sig
+  val ellipsis : string
+  val linked_arrow : string
+  val tree_last : string
+  val tree_middle : string
+  val tree_pipe : string
+end
+
+module HTTP : sig
+  val request :
+    ?timeout_span:float ->
+    Fetch.requestMethod ->
+    string ->
+    headers:(string * string) Rrbvec.t ->
+    body:string ->
+    (Fetch.Response.t * string) Cli_effect.t
+end
+
+module Crypto : sig
+  val sha256_hex : string -> string
+  val sha256_base64url : string -> string
+  val random_base64url : int -> string
+  val base64url_decode : string -> string
+end
+
+module Events : sig
+  type subscription = { close : unit -> unit Cli_effect.t }
+
+  val connect :
+    url:string -> on_chunk:(string -> unit) -> subscription Cli_effect.t
+end