feat: inject effort as soft default via CLI flags instead of env var (#104)

CLAUDE_CODE_EFFORT_LEVEL hard-locks effort for the whole session and makes
Claude reject in-session /effort switching (incl. ultracode). Carry effort
as a dedicated payload field instead, injected at spawn as a soft default:

- regular levels (incl. max) -> claude --effort <level>
  (the settings effortLevel key is enum([low,medium,high,xhigh]) with
  .catch(undefined), so max would be silently dropped there)
- ultracode -> claude --settings '{"ultracode":true}'
  (dedicated boolean settings key, rejected by the --effort flag)

Changes:
- add effort enum field to create/quick-start/ralph-loop schemas and thread
  it through Session -> CreateSessionOptions/RespawnPaneOptions -> spawn
- buildEffortCliArgs() in session-cli-builder, shared by tmux spawn command
  and direct-PTY fallback args
- frontend: buildEnvOverrides() no longer emits CLAUDE_CODE_EFFORT_LEVEL;
  validated effort goes into payloads via getEffortSetting()
- settings UI: add Ultracode option to the Thinking Effort dropdown
- legacy migration: Session constructor extracts CLAUDE_CODE_EFFORT_LEVEL
  from persisted envOverrides; applyEnvOverrides() unsets the stale tmux
  session var so respawned panes are no longer locked
- tests: test/effort-injection.test.ts (13 cases)

Co-authored-by: Teigen <teigenzhang@gmail.com>

src/mux-interface.ts

@@ -14,6 +14,7 @@ import type {
   ClaudeMode,
   SessionMode,
   OpenCodeConfig,
+  EffortLevel,
 } from './types.js';
 
 /**
@@ -63,8 +64,10 @@ export interface CreateSessionOptions {
   openCodeConfig?: OpenCodeConfig;
   /** When restoring after reboot, resume a previous Claude conversation by its session ID */
   resumeSessionId?: string;
-  /** Extra env vars exported before launching the CLI (e.g., CLAUDE_CODE_EFFORT_LEVEL). Ephemeral — not written to disk. */
+  /** Extra env vars exported before launching the CLI (e.g., CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS). Ephemeral — not written to disk. */
   envOverrides?: Record<string, string>;
+  /** Claude CLI effort level, injected as a `--settings` soft default (overridable via /effort in-session) */
+  effort?: EffortLevel;
 }
 
 /** Options for respawning a dead pane. */
@@ -81,6 +84,8 @@ export interface RespawnPaneOptions {
   resumeSessionId?: string;
   /** Extra env vars exported before launching the CLI (preserved across respawns). */
   envOverrides?: Record<string, string>;
+  /** Claude CLI effort level (preserved across respawns, injected via `--settings`) */
+  effort?: EffortLevel;
 }
 
 /**