fix(hooks): debounce redundant first-message recall (closes #561)

[Adarsh-031]

Summary

The UserPromptSubmit hook ran a full auto-recall (Memory load + embedding search) on the first message of every session, duplicating the recall SessionStart had just injected. This adds a one-shot, time-windowed debounce so the first prompt skips that redundant work.

Changes

File	Change
_shared.py	Add mark_recall_injected() / consume_recall_injected(), RECALL_MARKER_DIR, and
TRUEMEMORY_RECALL_DEBOUNCE_SECONDS (default 60s)
session_start.py	Write the per-session marker after normal-run recall
user_prompt_submit.py	_try_auto_recall takes session_id; a fresh marker short-circuits before detection and the Memory
load
tests/ingest/test_recall_debounce.py	New: marker semantics + gate short-circuit (9 tests)

The debounce is one-shot (marker consumed on read) and self-cleaning, so only the first prompt after SessionStart is skipped; later prompts recall normally.

Test plan

• All tests pass (pytest tests/ -q -m "not network" — 1062 passed, 14 skipped)
• Lint clean on changed files (ruff check)

Notes

• A pre-warmed daemon/Unix socket to remove the ~90ms interpreter cold start is intentionally out of scope here; worth a separate issue.
• For reviewers: CI's repo-wide ruff check may flag a pre-existing F401 (unused import pytest) in
  tests/test_issue_566_forget_always_load.py. That already exists on main and is unrelated to this PR — happy to fix it in a separate change if preferred.