feat(site): hover the growth chart for per-sync date + delta tooltips

[Seungpyo1007]

Hovering the History growth curve snaps a marker + vertical guide to the nearest sync and shows a tooltip: date · total records · delta (+ per-category change). Touch supported. Removes the static start/current captions — that info now shows only on hover, per request. Refs #1

Closes #19

[TechEngineBot]

TechEngine change review: PASS

• PR: feat(site): hover the growth chart for per-sync date + delta tooltips #91
• Ref: fix/history-hover
• Commit: fa59a85
• Requested by: @Seungpyo1007
• Run: https://github.com/GetTechAPI/TechEngine/actions/runs/28071242617

Check	Result
python -m app.validate	PASS
python integrity_check.py TechAPI/data --strict	PASS
cd TechAPI/site && npm ci && npm run build	PASS

Changed data

Category	Added	Modified	Deleted	Added verified	Added unverified	Added Kaggle-sourced
brand	0	0	0	0	0	0
soc	0	0	0	0	0	0
smartphone	0	0	0	0	0	0
tablet	0	0	0	0	0	0
watch	0	0	0	0	0	0
pda	0	0	0	0	0	0
gpu	0	0	0	0	0	0
cpu	0	0	0	0	0	0

Changed record examples

• No data file changes detected.

Heuristic review

• Heuristic warnings: none found.

Changed site

Area	Added	Modified	Deleted
homepage/site	0	2	0

Modified site files

• site/src/scripts/techapi.js
• site/src/styles/techapi.css

[TechEngineBot]

TechEngine validation stats: PASS

• PR: feat(site): hover the growth chart for per-sync date + delta tooltips #91
• Ref: fix/history-hover
• Commit: fa59a85
• Run: https://github.com/GetTechAPI/TechEngine/actions/runs/28071242617

Data summary

Category	Total	Verified	Unverified	Missing verified	Tracked	Verified % of tracked
brand	189	10	179	0	189	5.3%
soc	2104	123	1981	0	2104	5.8%
smartphone	90118	8453	81665	0	90118	9.4%
tablet	3048	174	2874	0	3048	5.7%
watch	378	11	367	0	378	2.9%
pda	110	27	83	0	110	24.5%
gpu	2030	244	1786	0	2030	12.0%
cpu	3977	986	2991	0	3977	24.8%
all	101954	10028	91926	0	101954	9.8%

Warning

Tracked verified coverage is below 50% for watch 2.9% (11/378), brand 5.3% (10/189), tablet 5.7% (174/3048), soc 5.8% (123/2104), smartphone 9.4% (8453/90118), all 9.8% (10028/101954), gpu 12.0% (244/2030), pda 24.5% (27/110), and 1 more.
Tracked coverage excludes records missing the verified field; see the Missing verified column for those records.
This does not fail validation. Keep imported records verified: false until manual audit, but treat this as follow-up verification work before relying on the affected categories as curated data.

Validation notes

• Full advisory outlier listings are suppressed on successful runs because they are dataset-wide and mostly stable between PRs.
• Failure runs still include a detailed log excerpt for debugging.

Key output:

## app.validate
## integrity_check.py --strict
loaded CPU=3977 GPU=2030
✅ integrity gate: no hard anomalies.

Integrity section	Flagged lines
structural	0
CPU name/tier consistency (desktop mainstream only)	0
CPU single>multi (cinebench/geekbench — should be multi>=single)	0
CPU era-vs-score outliers	8
CPU cross-source ratio outliers (possible wrong-variant)	152
GPU cross-source ratio outliers + sanity	18

Homepage build:

02:43:51 [build] 2 page(s) built in 48.52s
02:43:51 [build] Complete!