fix(launcher): pass root tsconfig to tsx, fix send help flags, match rlm attributes

[Ombhosalee19]

Summary

This PR addresses the following issues:

1. Source launcher tsconfig resolution (#904):
   Pass --tsconfig "$SCRIPT_DIR/tsconfig.json" to tsx in prime-agent.sh so monorepo workspace package aliases (such as @earendil-works/pi-agent-core) resolve correctly when prime-agent.sh is invoked from outside the repository directory.

2. Send command help flags (#901):
   Remove outdated --steer and --follow-up options from send command help spec in packages/coding-agent/src/cli/command-registry.ts.

3. Python rlm API handle and subagent attribute matching (#824):
   Add session_name property alias to RLMSpawnHandle and name property alias to RLMSubagent. Allow rlm.delete_subagent() to accept RLMSpawnHandle objects directly in addition to RLMSubagent and str.

Changes

• Modified prime-agent.sh
• Modified packages/coding-agent/src/cli/command-registry.ts
• Modified prime-agent-runtime/src/rlm/__init__.py
• Added packages/coding-agent/test/suite/regressions/904-source-launcher-tsconfig.test.ts
• Added packages/coding-agent/test/suite/regressions/901-send-help-options.test.ts
• Updated prime-agent-runtime/test/test_subagent_registry.py
• Updated packages/coding-agent/CHANGELOG.md

Testing

• npx tsx ../../node_modules/vitest/dist/cli.js --run test/suite/regressions/904-source-launcher-tsconfig.test.ts (passed)
• npx tsx ../../node_modules/vitest/dist/cli.js --run test/suite/regressions/901-send-help-options.test.ts (passed)
• PYTHONPATH=src python test/test_subagent_registry.py (passed)
• npm run check (all formatting, linting, tsgo, installer render, and browser smoke checks passed)

Fixes #904
Fixes #901
Fixes #824

Note

Fix source launcher tsconfig, remove stale send flags, and align RLM API attributes

• Adds --tsconfig "$SCRIPT_DIR/tsconfig.json" to the tsx invocation in prime-agent.sh so the launcher works correctly when run outside the repo directory.
• Removes deprecated --steer and --follow-up flags from the send command help spec in command-registry.ts.
• Adds session_name alias to RLMSpawnHandle and name alias to RLMSubagent in rlm/init.py so both types expose matching attributes.
• Extends rlm.delete_subagent to accept RLMSpawnHandle directly, deleting by rlm_child_id.
• Adds regression tests for all three fixes.

^{Macroscope summarized 2f5cb1a.}