fix(algorithm): A0 cross-model findings — priority, initialization, definition

A0 (Claude Sonnet, VPS) cross-model review findings:
- Stagnation Detection runs BEFORE L3 on shared iterations (priority defined)
- 'Consecutive' explicitly defined: sequential discards, keep resets counter
- experiments.tsv initial header includes think_reentries:0 and amplitude:normal

Author: rikitikitavi2012-debug

PAI/Algorithm/Algorithm-Autoresearch.md

@@ -79,7 +79,9 @@ For main Algorithm state, also read the PRD (see v4.0-alpha.md Context Recovery
 
 ### Stagnation Detection
 
-Track consecutive non-improvement results:
+Track consecutive non-improvement results ("consecutive" = immediately sequential discard rows in experiments.tsv, any `keep` resets the counter to 0):
+
+**Priority:** Stagnation Detection runs BEFORE L3 Structural analysis on applicable iterations (e.g., iteration 10 checks stagnation first, then L3).
 
 | Consecutive Discards | Action |
 |---------------------|--------|

PAI/Algorithm/v4.0-alpha.md

@@ -138,6 +138,8 @@ When iteratively optimizing `[Q]` criteria, log each attempt in `experiments.tsv
 ```tsv
 # metric_direction: higher_is_better
 # target: 90
+# think_reentries: 0
+# amplitude: normal
 iteration	commit	metric	delta	status	description
 0	a1b2c3d	62.0	0.0	baseline	initial measurement
 1	b2c3d4e	68.4	+6.4	keep	compress images with webp