fix: resolve code-review correctness bugs in README + build template

Three CONFIRMED defects, all from template/README text written before the
vo2max conflict section was revised, now reconciled with the corrected docs:

- README taper example said TSB '−5 to +5' (under-recovered) — corrected to
  the doctrinal +5 to +15 that periodization.md and both plan templates use.
- plan-template-build.md VO2 prescription said 'bias toward longer reps
  (3–5 min)... accumulate more time >90% VO2max than 30/30s' — contradicted
  its own cited source and was self-contradictory (140s ≠ 3–5 min). Replaced
  with the neutral menu: default medium (~2–4 min, near the ~140s optimum),
  short/long by goal, 'no rep length proven superior in cycling.'
- plan-template-build.md cited the phantom 'Yu et al.' (marked ❌ NOT FOUND in
  citations.md) — re-grounded the frequency heuristic in Seiler 2024.

DRY findings (inline PMID/DOI duplication, restated rhythm/field-test tables)
left as-is: inline citations and self-contained, independently-loadable docs
were explicit design requirements for this skill.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TqrhBhC3GEcKyaw8RTk8G6

README.md

@@ -23,8 +23,8 @@ number; ask this skill what to do about it.
 1. **MCP** returns the data — e.g. `get_athlete_summary` (CTL/ATL/TSB), `get_wellness_data`
    (HRV, RHR, sleep), `get_athlete_power_curves`, `get_activities`.
 2. **Skill** supplies the reasoning — e.g. "TSB is −25 eight days out from an A-race; the taper
-   doc says pull it toward −5 to +5 by race day," or "this VO2 session accumulated little time
-   ≥90% VO2max; the interval doc says lengthen the reps."
+   doc targets +5 to +15 by race day, so shed fatigue," or "this VO2 session banked little time
+   ≥90% VO2max; the interval doc says check whether rep length / work:rest kept power in the band."
 3. **You (Claude)** combine them into a recommendation, always citing which layer supplied what.
 
 ## Repository layout