feat(omo): retire opencode and move its skills and commands to omo

- Move the vendored skills from .config/opencode/skills to
  .config/omo/skills, with provenance and local changes in its README
- Rewrite Impeccable's script paths to ~/.omo/agent/skills/impeccable so
  its detector and live-server verbs resolve under omo
- frontend-workflow hands screenshots to a visual-engineering task
  instead of opencode run
- Move the notes commands and /impeccable to .config/omo/prompts as omo
  prompt templates; setup-mcp stays behind because it writes
  opencode.json
- Archive DEVELOPMENT-WORKFLOW.md and UI-WORKFLOW.md under
  .config/omo/archive; nothing loads them
- link-ai-configs.sh links the skills into omo and Claude Code only and
  stops linking OpenCode's config, TUI, plugins and workflow docs
- setup-mac.sh and Brewfile.apps stop installing OpenCode; README and
  .withcontextconfig.jsonc follow the new layout

~/.config/opencode/AGENTS.md stays linked: omo's rules engine reads it
before ~/.claude/CLAUDE.md and stops at the first hit, so it carries the
shared preferences and keeps OMC's instructions out of omo.

.config/omo/skills/cold-email/references/subject-lines.md

@@ -0,0 +1,53 @@
+# Subject Line Optimization
+
+The subject line determines whether the email gets read. The data is counterintuitive: **short, boring, internal-looking subject lines win decisively.**
+
+## Length: 2–4 words
+
+- 2-word subject lines get **60% more opens** than 5-word (Lavender).
+- Going from 2 to 4 words reduces replies by **17.5%**.
+- 2–4 words yield **46% open rates** vs 34% for 10 words (Belkins, 5.5M emails).
+- Mobile truncates at 30–35 characters — brevity is practical necessity.
+
+## Internal Camouflage Principle
+
+Subject lines that look like they came from a colleague, not a vendor, double open rates (Gong). Buyers mentally categorize before opening — if it looks like sales, it's filtered.
+
+**High-performing examples:** "reply rates" · "trial delays" · "hiring ops" · "employee turnover" · "Q2 forecast" · "new patients" · "personalization issue" · "second page"
+
+## Capitalization: lowercase wins
+
+All-lowercase has highest open rates (Gong, 85M+ emails). Lowercase looks more personal/internal. For cold outreach specifically, lowercase beats title case.
+
+## Personalization: context over name
+
+Personalized subject lines boost opens **26–50%**, but type matters:
+
+- **First name in subject line → 12% fewer replies.** Signals automation.
+- **Contextual personalization works:** pain points, competitors, trigger events, industry challenges.
+- Use {{painPoint}}, {{competitor}}, {{commonGround}} — not {{firstName}}.
+
+## Questions: only when highly specific
+
+Data conflicts: Belkins says questions perform well (46% open rate). Lavender says questions lower opens by **56%**. Resolution: **specific pain questions work** ("Need help with {{challenge}}?"), **generic questions fail** ("Quick question?" / "Have 15 minutes?"). Default to statements.
+
+## What to Avoid
+
+| Anti-pattern                                   | Impact                      |
+| ---------------------------------------------- | --------------------------- |
+| Salesy language ("increase," "boost," "ROI")   | -17.9% opens                |
+| Urgency words ("ASAP," "urgent")               | Below 36% opens             |
+| Excessive punctuation ("!!!" or "??")          | -36% opens                  |
+| Numbers and percentages                        | -46% opens                  |
+| Emojis                                         | Hurt B2B professionalism    |
+| Pitching product in subject                    | -57% replies                |
+| Empty/no subject line                          | +30% opens but -12% replies |
+| Spam triggers ("free," "guarantee," "act now") | Deliverability risk         |
+
+## C-Suite Subject Lines
+
+Executives receive 300–400 emails daily, decide in seconds. They respond **23% more often** than non-C-suite when emails pass their filter (6.4% reply rate).
+
+What works: ultra-concise, human, understated. "{{companyInitiative}}" · "thank you" · "an update" · "a question" · reference to a specific project or trigger event.
+
+Anything "salesy" is immediately rejected.