Add transaction accelerator (prioritisetransaction UI + API)

Full-stack feature for boosting transactions via bitcoind's
prioritisetransaction RPC:

Backend:
- New accelerator package with Accelerate, Cancel, MaxFeerate, List,
  and background Cleanup goroutine (removes confirmed/dropped txs)
- RPC wrappers: GetMempoolEntry, PrioritiseTransaction,
  GetRawMempoolVerbose, IsRPCError helpers
- SQLite boosted_txs table for persistence across restarts
- Revenue impact measured via getblocktemplate before/after comparison
- Hard cap at 2000 sat/vB; MaxFeerate uses fees.base (not modified)
  to ignore our own prior priority adjustments

Frontend:
- Rocket icon in header with 10s jiggle animation
- AcceleratorPage with flame-gradient border, txid input, feerate
  input, "Prioritize above all" button with spinner, boost list with
  cancel buttons, and dismissible error/success messages
- Hash-based routing (#/accelerator)
- SharesBar font size bump

api/internal/httpapi/server.go

@@ -10,18 +10,20 @@ import (
 	"net/http"
 	"strings"
 
+	"github.com/kamadopool/kamado-api/internal/accelerator"
 	"github.com/kamadopool/kamado-api/internal/state"
 	"github.com/kamadopool/kamado-api/internal/webui"
 )
 
 type Server struct {
 	Agg *state.Aggregator
+	Acc *accelerator.Service
 	Hub *Hub
 	Log *slog.Logger
 }
 
-func New(agg *state.Aggregator, log *slog.Logger) *Server {
-	return &Server{Agg: agg, Hub: NewHub(), Log: log}
+func New(agg *state.Aggregator, acc *accelerator.Service, log *slog.Logger) *Server {
+	return &Server{Agg: agg, Acc: acc, Hub: NewHub(), Log: log}
 }
 
 // Handler returns an http.Handler with all kamado routes mounted under
@@ -39,6 +41,10 @@ func (s *Server) Handler() http.Handler {
 	mux.HandleFunc("GET /api/ws", s.handleWS)
 	mux.HandleFunc("GET /api/admin/debug-blocks", s.debugBlocks)
 	mux.HandleFunc("POST /api/admin/reset-latency", s.resetLatency)
+	mux.HandleFunc("POST /api/accelerate", s.accelerate)
+	mux.HandleFunc("POST /api/accelerate/cancel", s.accelerateCancel)
+	mux.HandleFunc("POST /api/accelerate/max", s.accelerateMax)
+	mux.HandleFunc("GET /api/accelerate/list", s.accelerateList)
 	mux.Handle("/", spaHandler(webui.FS()))
 	return mux
 }