Clarify IPO short-exit strategy horizon

Request:
- Emphasize that the analyst model is for selling allocated IPO shares in T2 grey market or on D1, not for long-term holding.

Changes:
- Add explicit T2/D1 sell discipline to the analyst skill.
- Update ipo_score_v0 targets and holding policy so D1 sell return is primary and T2 is the intended extension when reliable grey-market data exists.
- Clarify that D5/D20/D60 are review labels only, not planned holding targets.
- Update the model report, single-ticker report generator, README, and the 06106 report language to reflect the short-exit horizon.

Verification:
- Rebuilt the model report with the same dataset timestamp and confirmed the analysis dataset did not change.
- Ran py_compile for build_analysis_dataset.py and generate_ipo_report.py.
- Generated a 06106 dry-run report showing T2/D1 exit discipline.
- Ran git diff --check.

Next useful context:
- T2 is still disabled in v0 until archivist approves a reliable grey-market data source; D1 remains the live modeled sell label.

rules/ipo_score_v0.yaml

@@ -7,14 +7,27 @@ purpose: >
   Build the first transparent Hong Kong IPO subscription scoring model from
   archived project data. The model is a rules-plus-calibration baseline, not a
   black-box predictor. It separates T0 prospectus information from T1 allotment
-  information so later facts do not leak into earlier decisions.
+  information so later facts do not leak into earlier decisions. It is designed
+  for short IPO subscription exits, not long-term holding.
 
 targets:
-  primary: D1 return versus IPO offer price
+  primary: D1 sell return versus IPO offer price
   secondary:
-    - D5 return versus IPO offer price
-    - D20 return versus IPO offer price
-    - D60 return versus IPO offer price
+    - T2 grey-market sell return versus IPO offer price, disabled until a reliable source exists
+    - D1 strong-return probability
+
+holding_policy:
+  intended_exit_window:
+    - T2_grey_market when a reliable grey-market price is available
+    - D1 otherwise
+  default_assumption: sell allocated shares by D1
+  non_targets:
+    - D5 return
+    - D20 return
+    - D60 return
+  note: >
+    D5/D20/D60 outcomes are retained for review and error attribution only.
+    They do not define the subscription model's target holding period.
 
 stage_policy:
   T0_prospectus:
@@ -147,4 +160,4 @@ known_limitations:
   - T1 is structurally complete for listed rows, but some individual demand fields remain null when the archived source does not explicitly state them.
   - Industry labels and issuer fundamentals are not yet sufficiently structured for v0.
   - T2 grey-market signal is intentionally disabled until a reliable source exists.
-  - Current D1 outcomes are from archived market data and should be reviewed for extreme corporate-action or data-vendor anomalies.
+  - Current D1 sell-return outcomes are from archived market data and should be reviewed for extreme corporate-action or data-vendor anomalies.