feat(pricing): restore TB perpetual calculator with reworked pricing model

[rusikv]

Restores the ThingsBoard PE perpetual license calculator removed in #485, updated to the current perpetual licensing model as sold on the License Portal.

What's in

Pricing model

• Base license includes 5,000 devices + 1 production instance ($4,999), 5M AI credits, and white labeling.
• Symmetric device/instance scaling: each purchased production instance ($4,999) also grants +5,000 devices; every full 5,000 purchased extra devices unlocks 1 complimentary production instance (no extra device capacity — no double counting). The devices field always shows the resulting quota (5,000 + extras + 5,000 × instances, capped at 1M on every path), and the caption under it + the instances helper render from the same state, e.g. 5 000 included + 5 000 included from instance + 7 000 extra devices.
• AI Credits stepper (1 = 1,000,000 credits; 5 packs included). Extra packs have no public list price, so requesting them routes to the custom-pricing flow.
• Add-ons: Edge $849 (2 incl., $399/extra), Trendz $1,499 + $0.30 × every device beyond the base 5,000 (incl. instance-granted), Offline $19,999, dev instance $999.

Custom pricing — total ≥ $24,998, Offline Mode, or extra AI credits

• The calculation summary is replaced by a centered personal-price notification (tag icon + "Get a personal price for these numbers" — "Get a personal price" when Offline Mode is the only selection), Total shows "Custom", and a Send request CTA opens Contact Us prefilled with the configuration — quantities only, no prices.
• Base + Offline = exactly $24,998, so Offline always routes to a personal quote, as intended.

Implementation — the calculator predates several refactors, so it's rewritten on current conventions rather than reverted: modal lifecycle via modal-controller (portal-to-body + scroll-lock), analytics via calc-analytics with a new tb_perp CalculatorType (calculator_open / calculator_interaction / calculator_export / calculator_cta_click; interaction adds calculator_ai_credits + calculator_addon_offline; total is null and plan is Custom at the custom tier), shared export buttons, @-prefixed import aliases.

Page wiring: hero card regains the "Estimate your cost" primary CTA (window.openTbPerpCalc), secondary Contact Us keeps the autofill message; modal mounted next to the PAYG/Private Cloud modals; FAQ data-open-calc="perp" branch restored. The pre-removal tbPerpetualPlans export was dead code and stays removed.

Shared polish: the Reset button label is now vertically centered and its height matches the footer CTA (36px box under a 24px text line left the label sitting low — affected all calculator modals).

Verification

• astro check — 0 errors; full astro build — success.
• Playwright end-to-end against the built site — 51 checks: default $4,999 total and summary rows; 12,000 devices → $11,999 + 1 complimentary instance; +1 purchased instance → quota 17,000 / $16,998 with synced captions; Trendz $22,097; custom wall for threshold / Offline / extra AI packs with both wording variants and price-free Send-request message; GTM events (tb_perp, null total + Custom plan at the custom tier, calculator_ai_credits, export carrying plan+total); typed sub-minimum AI values clamped before the debounced GTM push; 1M device cap held when instances raise the floor; emptied instances field keeps purchases; Reset; Escape close.