chore(release): v3.3.0

~75 PRs merged since v3.2.0 plus 7 community fixes salvaged via PR triage.

Highlights:
- Install everywhere: npx skills add is canonical for Claude Code, Codex,
  Cursor, Gemini CLI, Copilot, Windsurf, and 50+ Agent Skills hosts.
- New emit mode: --emit=html for shareable HTML briefs.
- New source: Digg (auto-enabled when digg-pp-cli on PATH).
- New env vars: EXCLUDE_SOURCES, LAST30DAYS_YOUTUBE_SSH_HOST.
- New credential source: macOS Keychain.
- Reliability sweep: Reddit (4xx + URL prefix + multi-key auth), xAI
  error surfacing, Windows compatibility, YouTube/HN unblock,
  HTTP retries, planner gating, render fixes.
- Multi-harness reframe: AGENTS.md becomes canonical, CLAUDE.md points
  at it. SKILL_ROOT → SKILL_DIR substitution.

Breaking:
- .codex-plugin/plugin.json removed. Codex installs via npx skills add.

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "last30days-skill"
-version = "3.2.4"
+version = "3.3.0"
 description = "Multi-source last-30-days research skill"
 readme = "README.md"
 requires-python = ">=3.12"